(svn r7451) -Fix (7372): GetNum(Towns|Industries) should return the actual number of towns and industries.
-Fix (6055): GetMax(Town|Industry)Index should not return the number of towns or industries - 1, but the size of the pool - 1.

(svn r7331) - Codechange: Rename all memory pool macro's and types to "old pool", so the new pool implementation can be committed alongside it.
- Codechange: Rename pool.[ch] to oldpool.[ch].

(svn r6149) -Codechange: DeleteTown removes a town from the pool
-Codechange: DestroyTown is called by DeleteTown to remove all things where a town depends on.
Last 2 changes to prepare for new pool system. Not pretty now, will be soon.

(svn r6058) -Fix: Get(Industry|Town)ArraySize could never return 0
Note: _total_towns and _total_industries willb e removed soon, so this 'hack' is okay, for now ;)

(svn r6055) -Codechange: added GetXXXArraySize, which returns HighestID + 1 (or, will do that).
It isn't the best name, but we couldn't find any better.
This unifies the pool-system even more.

(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 r6047) -Codechange: FOR_ALL now _only_ loops valid items, and skips invalid ones
-Codechange: use IsValidXXX where ever possible
Note: both changes to prepare for new pool system, which needs those changes.
For every pool there are 2 ugly lines, which will be removed when done
implementing new pool system.
Based on FS#13 by blathijs, partly implemented.

(svn r4591) -Fix (FS#122) Game no longer errors out when "Many random towns" is selected in the scenario editor.
-Side effects:
- Removed one global variable from variables.h
- Remove an ugly hack for the "many random towns" function

(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 r2288) - CodeChange: protected the next batch of commands (41 so far, out of 115).
- CodeChange: changed the airport gui airport-type checking. Added function GetValidAirports() that returns bitmasked availibility, is also used for checking.
- CodeChange: to check tree-planting, 2 const arrays have been moved to table/tree_land.h (type and count)
- CodeChange: added IsTownIndex() in following of IsStationIndex(), etc.
- Fix (regression): road tunnels did not work anymore, forgot that their type was 0x200 (documented now)

(svn r1866) -Fix: Intercepted generated maps with 0 towns on it. Currently just an
error() is called, some more graceful handling should be implemented
later.

(svn r1834) - Fix: NPF does not check the owner of its target, busses try to enter other players' depots. TODO
- Add: asserts to find the v->u.rail.track == 0 problem.
- Add: IsValidDepot(), IsValidTown(), IsValidSign(), IsValidVehicle(), IsValidStation()
- Add: GetTileOwner(), IsTileOwner()
- Codechange: Replaced IsShipDepotTile(), IsTrainDepotTile(), IsRoadDepotTile() by IsTileDepotType().
- Codechange: typedeffed the MAP_OWNERS as Owner. Should be used as variable type.
- Codechange: Replaced a few uint by TileIndex.

(svn r1764) -Add: dynamic towns, you can now have up to 64k towns (let me know when
you have that amount of towns in a map ;))

(svn r1407) -Codechange: changed a lot around _stations, _vehicles, _towns and _industries
(in prepare of dynamic arrays):
- DEREF_XXX is changed into GetXXX
- All direct call are directed via GetXXX
- struct Industry has now an index-field
- ENUM'd some stuff
- Replaced home built loops with FOR_ALL_XXX
- Added _stations_size, _vehicles_size, ... which gives the length of the
array (which will be dynamic in the near future)
- Changed lengtof(XXX) to _XXX_size (e.g. _stations_size)
- Removed all endof(XXX) (because mostly it was part of a FOR_ALL_XXX)
- Made the sort-functions of all 4 dynamic
- Made all 4 Initialize functions more of the same
- Some minor tab-fixing and stuff
(tnx to Tron for proof-reading my 100kb patch ;))

Note for all: please do NOT directly call _stations, _vehicles, _towns and
_industries, but use the right wrapper to access them. Thank you.
Ps: please also do not use 'v++', where v is of type Vehicle *.

(svn r1312) -Add: Patch which is on by default: population in label of the town
-Fix: Expand town is a bit more agressive
-Fix: Fixed a bug in growing algorithm

(svn r1291) -Codechange: prepared subsidies and towns to become an uint16 (happens
after savegame bump)

(svn r122) Change: exclusive transport rights are now stored per town instead of per station
Exclusive rights from old savegames will be reset.

(svn r5) -Fix: townname generation of TTDLX savegames. All work
except for German Townnames (also fix one typo on
English town-names)
-CodeChange: *act_paper to *act_water in Town to
more resemble its use
-Fix: AI players now retain AI status. Since TTDLX
savegame status is not fully documented, some holes
exist (AI state is set to one without a vehicle, otherwise
it crashes)