(svn r4323) -Regression: Clear the slot assignments of all vehicles heading twoards a road stop if that road stop gets removed
This issue was fixed in r2210 and reintroduced in r4259 when the multistop handling was overhauled.

(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 r4113) Moved all relevant map functions for stations to station_map.[ch]
Some work with animated tiles remains. Thanks to Tron for parts of the code and lots of proof-reading and suggesting

(svn r3996) -Fix: Slope and height information returned for some tile types is wrong
This leads to graphical glitches when drawing foundations.
This doesn't fix all problems, but at least some of them.

(svn r3895) - Add proper SLE(G)_CONDNULL macros for the empty space reservation in savegames and update where used
- Also add this capability to settings

(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

(svn r3472) - [PBS] Remove from trunk. Anyone interested can still find it in branch/pbs. This reverts revisions r3158, r3140, r3075, r2977, r2674, r2625, r2621, r2529, r2528, r2525, r2524, r2519, r2517, r2516, r2507, r2499. (in conjunction with Tron)
- The only change is that the nsignalsw.grf file is kept and that existing nightlies with PBS signals get those signals converted to combo-signals.

(svn r3313) Remove GPMI related changes from trunk
Revisions in detail: 2542, 3226 (partial), 3229, 3231, 3232, 3238, 3242-3245, 3251, 3253, 3260, 3263, 3265, 3266, 3269, 3277, 3278, 3279, 3283 (partial), 3304, 3305, 3306

(svn r3232) -Add: implemented the event-system for AIs
-Add: added several hooks (event-callbacks) for road-related-stuff

(svn r3218) -Feature: Multiheaded train engines will now stay in the same train
This means that any user attempt to remove a rear engine will tell the user to move the front engine instead
This fixes the assert when moving multiheaded engines (introduced in r3144)
Note: to make old savegames use this feature, some engines might be turned around in order to link engines in pairs

-Codechange: train subtype is now a bitmask
This allows fast access to info like if it is a wagon or engine and if it is in front and so on
Note: savegame version bump

(svn r3181) -Bracing
-Indentation
-Whitespace
-DeMorgan's Law
-Test with NULL or 0 for non-booleans
-'\0' instead of 0 for chars
-Remove redundantly redundant comments (like DoFoo(); // Do foo)
-Join multiple short lines with a single statement
-Split single lines with multiple statements
-Avoid assignments in if

(svn r3173) Use the trinary operator and switch to improve readability
Also align short cases nicely

(svn r3167) - NewGRF: Start moving custom station code to separate files.
Rewrite handling of station classes.
Allow for more than 8 station tile layouts.
Start of code to unload custom stations.

(svn r3155) -Feature: [autoreplace] autoreplace can now remove cars from too long trains
-Trains will now remember the length of stations it visits and sell cars
when being autoreplaced if they became too long
-If it needs to remove cars, then it starts from the front and sells
all it can find until the train is short enough
-This only works for trains, that knows the station length of the route
so a full uninterrupted run is needed
-a train needs 1-2 runs to detect if the shortest station is expanded
-This feature can be turned on and off in the train replace window
and each company can have it's own setting
-NOTE: minor savegame version bump

(svn r3078) Some more stuff, which piled up:
- const, whitespace, indentation, bracing, GB/SB, pointless casts
- use the trinary operator where appropriate
- data types (uint[] -> AcceptedCargo, ...)
- if cascade -> switch
- if (ptr) -> if (ptr != NULL)
- DeMorgan's Law
- Fix some comments
- 0 -> '\0', change magic numbers to symbolic constants

(svn r3077) static, const, bracing, indentation, 0 -> '\0'/NULL, typos in comments, excess empty lines, minor other changes
nothing spectacular, just some stuff, which piled up

(svn r2962) - const correctness for all Get* functions and most Draw* functions that don't change their pointer parameters
- change a lot of byte player types to PlayerID
- beautify header files, same "#endif /* filename */" ending

(svn r2951) - Fix: [ 1259345 ] Changing engine in netgame opens train window for everyone
- Add IsLocalPlayer() which substitutes _local_player == _current_player

(svn r2948) -Fix: the old AI needs a special flag that triggers all kind of special
abilities you really don't want to know about (free bridges, etc..)
I removed this flag some revisions ago, but the Aircraft part
depends on it, so I re-enabled it again..

(svn r2921) -Codechange: moved all AI-code to 1 central place (ai/ai.c)
-Fix: removed the ability for the oldAI to cheat (this will criple him somewhat)
-Add: base-code for many improvements to come in the AI-system
-Add: added base-code for multiplayer AIs (DOES NOT WORK YET!)

(svn r2702) -Codechange: Cleaned up the sprite code and replaced many magic numbers
by enums. There remains work in gfx.c to move the "transparency" and
"recolor" bits around to make space for more sprites. However, 2800
additional sprites can now be loaded. There also remains cleanup and
Doxygen work on many of the header files.

(svn r2595) -Codechange: Introduced "IsSteepTileh" to find whether a tile is steep
(i.e. spans two height levels) and use it throughout the code.
-Codechange: Add CanBuildDepotByTileh to find if a tile is suitable to
build a depot on it. Wraps some bitmagic which seems quite unreadable at
first glance

(svn r2516) - Feature: [pbs] Implement path-based-signalling. This allows multiple trains within the same signal block, provided their paths dont intersect. For this the block must have all exit and entry signals be pbs signals. Place these by ctrl-clicking 4 times on a normal signal.
- Feature: [pbs] Implement autoplacement of pbs blocks, when a block has an entry and an exit pbs signal, covert the entire block to pbs. Can be turned off in the patch settings.
- Feature: [pbs] Allow showing of reserved status by making the tracks darker, when the pbs debug level is at least 1.

(svn r2448) General cleanup of rail related code, more to follow.
* Add: rail.[ch] for rail-related enums and wrapper functions.
* Codechange: Removed dozens of magic numbers with below enums.
* Codechange: Rewrote CheckTrackCombination().
* Add: TILE_SIZE, TILE_PIXELS and TILE_HEIGHT constants.
* Add: enums RailTileType, RailTileSubtype, SignalType to mask against the map arrays.
* Add: enums Track, TrackBits, Trackdir, TrackdirBits for railway track data. (Note that the old RAIL_BIT constants are replaced by TRACK_BIT ones).
* Add: enums Direction and DiagDirection
* Codechange: Moved a bunch of track(dir) related lookup arrays from npf.[ch] to rail.[ch].
* Codechange: move RailType enum from tile.h to rail.h.
* Add: Wrapper functions for masking signal status in the map arrays: SignalAlongTrackdir, SignalAgainstTrackdir and SignalOnTrack.
* Add: Wrapper functions to access rail tiles, using above enums
* Add: Wrapper functions to modify tracks, trackdirs, directions, etc.
* Add: Wrapper functions for all lookup arrays in rail.[ch] (Arrays are still used in parts of the code)
* Codechange: Renamed some variables and arguments to better represent what they contain (railbit -> track, bits -> trackdirbits, etc.).
* Codechange: Don't use FindLandscapeHeight() in CmdRemoveSingleRail(), since it returns way too much info. Use GetTileSlope() instead.
* Codechange: [NPF] Removed some unused globals and code from npf.c.

(svn r2387) - CodeChange: made the saveload code more readable and also removed the 'byte' saveload arrays which means you can save an array of more than 255 elements, or bigger structs than 255 bytes. This doesn't yet solve the problem that a chunk can be a maximum of 16384 big.
- Fix: also fix an unnoticed error in SlSaveLoadConv() due to wrong types.