(svn r7565) -Codechange: Rework DEBUG functionality. Look for appropiate debugging levels to
use in debug.h. grfmsg() is now used as a specific debug-function for grf.

(svn r7386) -Codechange r7385: moved deletion of the vehicle highlight from DeleteVehicle to the sell commands as they are not called as often
Also added a return to the window loop prevent looking at the rest of the windows once the right depot window is found

(svn r7330) -Fix (r7304): Data invalidation doesn't always happen as the local
player, resulting in an empty vehicle purchase list. Specify the player
as an argument to IsEngineBuildable()

(svn r7313) -Codechange: Calling invalidate data on a window will surely warrant a redraw, so call
that after the WE_INVALIDATE_DATA event and remove (some of) the superflouous calls.

(svn r6771) -Codechange: Replace two macros with functions. IS_HUMAN_PLAYER and
IS_INTERACTIVE_PLAYER

(svn r6651) -Coding feature: added the windowevent WE_INVALIDATE_DATA
This gives the ability to invalidate some window data and recalculate as needed instead of doing it for each WE_PAINT

This event is called right away when using InvalidateWindowData(), so it may be a good idea to set a bool or similar in the window
or similar and then act on that bool in WE_PAINT instead of doing a lot of stuff in WE_INVALIDATE_DATA as it might be called more than once before WE_PAINT is called

InvalidateWindowData() will not automatically repaint the window, so if you want to repaint it as well, you need to mark it dirty as well.

Made the depot windows use WE_INVALIDATE_DATA to set when to generate the engine and wagon lists instead of at each redraw
It makes no sense to regenerate the list when say using the scrollbar if we know that no vehicle have entered or left the list

NOTE: currently there is a piece of code to generate the list when it's not needed and compare it to the stored list and assert if they mismatch
This check is somewhat slow and kills the whole idea of WE_INVALIDATE_DATA, so it's a short lived one to verify that InvalidateWindowData() is used everywhere where it's needed

(svn r6637) -Codechange: merged all (vehicle type)EnterDepot into VehicleEnterDepot()
This revealed duplicated code like aircraft lists got invalidated twice
Moved invalidation of the vehicle detail window to VehicleServiceInDepot() as it should always be updated when serviced

(svn r6624) -Feature: added ability to add refit commands to vehicle orders (can only be done in goto depot orders)
Example: make a train transport iron ore from A to B, then it visits a depot and refits to steel
It then transport steel back to A or near A if there is a factory and then it visits another depot to refit to iron ore again

This is controlled in the orders. If a goto depot order is lightlighted, then "Unload" changes to "Refit"
Control click "Refit" removes the refit part of the order (as the tooltip says)
The player will still pay the normal refit costs

Known issues:
If a vehicle is not in a depot, then the refit window will fail to tell refitted cargo capacity
Refit costs in the refit window can sometimes print 0 when it should not because the refit calculation is unaware that the vehicle will be refitted in between

Warning: autoreplace got a protection against replacing something so you get a new cargo type, but it can fail here. In the iron ore/steel example, it can see that
the vehicle carries iron ore and the new one can be refitted to iron ore, then it will replace. It will not check to see that it's valid for steel as well.
This is something to look into in the future

(svn r6424) -Codechange: [autoreplace] removed a loop though all vehicles from each time the window is redrawn
To do this, the player struct contains an array, that contains the count of each engine type that the player owns
Those arrays are updated each time a vehicle is build or deleted and is calculated on load (it's not saved)
It's possible to access the arrays outside of the autoreplace GUI, so feel free to read from them in other patches as well

(svn r6406) -Codechange: Rename TileOffsByDir to TileOffsByDiagDir because it accepts
DiagDirections, and add TileOffsByDir that handles Directions.
-Codechange: Make the treeloop use TileOffsByDir().

(svn r6381) -Cleanup: make the '/* */' comments that span multiple lines more uniform.
-Cleanup: whitespace alignment of a few tables.

(svn r6376) -Codechange: [vehicle refit] moved all refit cost calculations into GetRefitCost()
Now it's possible to tell refit costs for an EngineID without actually having build a vehicle

(svn r6356) -Fix: FS#263 planes come out of hangar and drive back into hangar
Now all vehicles are serviced when it's time for service and they are in a depot
This will avoid the goto depot order from ever showing up when in a depot

(svn r6353) -Codechange: Make DestinationID a typedef of uin16, which is as large as any type of destinataion (StationID, DepotID, WaypointID) it can hold
DestinationID being a union of these types is just hassle without benefit and cannot be handled correctly everywhere because of local lack of information

(svn r6352) -Fix: FS#322 Send to depot bug
now vehicles can't be sent to a depot when they are already inside a depot
before they would remember the order and try to turn around when leaving the depot

(svn r6291) -Feature: Vehicle lists from the station window now also got the goto depot button
-Codechange: unified the code for mass goto depot to avoid duplicated code
-Fix: Vehicles already on the way to depots will not be cancelled by mass goto depot (made it really hard to send all vehicles at once)

(svn r6246) -Feature: added the many times requested "send all vehicle to depot" button
it's located in the vehicle list screen and does the same as in the shared orders window (send all vehicles in list to a depot)
it will still not inform the player if a vehicle failed to find a depot, so don't take for granted that all of them go

(svn r6229) -Feature: Shared order lists now got a "goto depot" button
this will try to send all vehicles in the list to depots/hangars
currently if one fails to find a depot, it will not tell the player

(svn r6165) -Feature: control click Goto Depot will now make the vehicle service
at the depot and leave right away.
To tell the difference the status of stopping vehicles will be in red,
while servicing vehicles will be green.
-Codechange: remove some dead code in CmdSendAircraftToHangar() since it is
conflicting with new functionality. Now p2 means the same for all types

(svn r6142) -Codechange: added WaypointID (sorry DV, couldn't splits it anymore)
-Codechange: introduced DestinationID, which is in fact an union of several types
Used in Order struct, so no longer StationID is abused for all targets.
Hangars are a big exception, as they use a station-id with GOTO_DEPOT (go figure)

(svn r6053) -Codechange: renamed all IsXXXIndex to IsValidXXXID
-Codechange: IsValidXXXID now also checks if XXX is really valid, not if the number is within range
Both changes again in preperation of the new mem-pool system, which requires this.
IsValidXXXID is not a bit less pretty, but that will be cleaned up after the new mem-pool system

(svn r6052) -Codechange: change OrderType (order->type) in a typedef
-Codechange: renamed DeleteDestinationFromVehicleOrder to RemoveOrderFromAllVehicles to reflect his function better
-Codechange: changed the params of RemoveOrderFromAllVehicles, to avoid unneeded variable-creation

(svn r5926) -Codechange: make _cur_year contain the full year, instead of the offset since 1920
-Codechange: store all year related variables that are _not_ stored in a savegame/transported over the network in the same format as _cur_year

(svn r5887) -Cleanup: move date related functions, defines and variables to date.[ch]
-Cleanup: fix whitespace related coding style issues in date.[ch]
-Cleanup: make original comments doxygen compatible and remove/change outdated comments

(svn r5070) Merged the bridge branch
-Feature: Bridges can now be placed above:
Any railway track combination (excluding depots and waypoints)
Any road combination (excluding depots)
Clear tiles (duh), including fields
Tunnel entrances
Bridge heads

Thanks to Tron for idea and implementation, KUDr for the yapf synchronization and many others for hours of testing

There are still a number of visual problems remaining, especially when electric railways are on or under the bridge.
DO NOT REPORT THOSE BUGS FOR THE TIME BEING please.

(svn r4826) -Fix: [autoreplace] fixed possible problem when autoreplacing and was number of vehicles (of a type, not total) was reached
now the new vehicle gets the same number as the old one, completely removing the problem where we could run out of numbers
since we don't have to find free numbers for the new vehicles, autoreplace should be somewhat faster, specially in late games
NOTE: in CmdBuildRailVehicle(), bit 0 and 1 in p2 have been switched to make the meaning of bit 0 consistent with the other build commands. CmdCloneVehicle() is modified to follow this as well

(svn r4342) Change the first two parameters of commands - virtual pixel coordinates of the tile to operate on - to a TileIndex
Remove DoCommandByTile(), because now it does the same as DoCommand()

(svn r4259) -[multistop] Fix/Feature/Codechange:
1) Improved the road vehicle allocation (aka slotting) for multistop. Stops can now accept unlimited, er... 256, vehicles.
2) Removed the "wait for stop" feature, because it did not work in practise.
3) Slotting now ignores unreachable stations. Uses NPF at the moment because the old pathfinder cannot do it (yet)
4) Now matter how many vehicles approach a station, they will always be distributed evenly over existing stops.
5) Hopefully the last fundamental change to multistop

(svn r3909) [multistop]
-Codechange: No longer hijack the VS_STOPPED flag when waiting for a slot.
-Fix: Vehicles waiting for slots can still be controlled (sent to depot, orders modified, ...)
-Fix: Vehicles no longer stop on crossings and during overtake operations

(svn r3757) -Feature: Delete news items about vehicles, when they get stale
This is used to delete
- all news about a vehicle, when it gets deleted
- "vehicle has stopped in depot" news, when it gets started
- "vehicle has invalid orders" news, when the orders get changed

(svn r3730) Multistop modifications:
-Codechange: Completely rewritten the slot assignment system. It now consumes less CPU cycles and memory
-Codechange: Increased maximum number of roadstops to 16.
-Fix: Several conditions where a slot becomes unliked from a vehicle
-Codechange: ClearSlot now only takes one parameter, the vehicle
-Feature: Console command 'clearslots' to clear ALL currently assinged slots. debug usage only
-Feature: vehicles that cannot get a slot now wait on the road instead of planlessly blocking stops or circling around
-Codechange: Adjusted debug levels
TODO: Make the slot finder compatible with (a) pathfinder(s).

(svn r3564) Several smaller changes:
- Don't treat non-booleans as booleans
- Reduce variable scope
- Bracing
- Use DeMorgan's law to make conditionals easier to read
- if cascade -> switch
- Replace some magic numbers by symbolic names
- Avoid assignments within other statements