(svn r7195) -Feature: [FS#297, optional elrails] New patches/vehicles option 'disable electrified railways'.
(original patch by maedhros, ideas: peter1138, Darkvater, Rubidium, Patrick, Eddi|zuHause, ..)

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

(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 r3329) - Doc: Some documentation cleanups.
- Add: TracksOverlap() (from the map branch), TrackdirBitsToTrackBits(), DiagdirReachesTrackdirs(), DiagdirReachesTracks().
- Fix: Infinite loop in the pathfinder introduces in r3321.

(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 r2798) -Codechange: Unified the rail toolbars into one that is modified by
request using the RailtypeInfo struct

(svn r2756) Renamed railtypes into _railtypes
Renamed railtypes.c into railtypes.h, all other tables are in .h files. (It should be in the tables dir but I couldn't figure out how to get it there without deleting it first).
Added const and extern.

(svn r2541) -Feature: Modified IsCompatibleRail so that an engine can move on more
than one railtype (like Diesel engines on electrified rail).
-Codechange: Use IsCompatibleRail where it should be used

(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 r2514) - Codechange: [NPF] Move the checking of railtype into a funciton IsCompatibleRail().
- Codechange: [NPF] Check the railtype along a route against the engine type instead of against the previouse tile. This clears the way for electriefied rails.
- Add: [NPF] [ 1209644 ] A penalty for crossings (peter1138)

(svn r2507) -Fix: Forgot to change an enum in rail.h in r2499 (thanks blathijs for
pointing it out)

(svn r2473) - Add: VehicleMayEnterTile(), which checks if the tile owner of a tile is correct for a vehicle to enter it. Based upon glx's code.
- Fix: [ 1203769 ] [NPF] NPF tries to plan over bridges, through tunnels, over level crossings of other players. (glx)
- Codechange: Renamed TRANSPORT_MAX to TRANSPORT_END and added INVALID_TRANSPORT.
- Codechange: Moved IsLevelCrossing() from tile.h to rail.h
- Add: GetCrossingTransportType(), which returns the transport type (road, rail) of both tracks on a level crossing.
- Removed old TODO that was fulfilled already.

(svn r2456) * Prettyfied npf.c using enums and wrappers from rail.h.
* Moved GetTileRailType() from npf.c to rail.[ch].

(svn r2454) * Codechange: Move #include "stdafx.h" and "openttd.h" from rail.h to rail.c
* Codechange: Move declaration of lookup arrays into the functions that need them. This doesn't pollute the global namespace with the array names.
* Add: rail.h to the openttd.vcproj and openttd.dsp for MSVC.

(svn r2450) * Codechange: Replaced all uses of the arrays in tile.h with calls to the associated wrapper functions.
* Codechange: Made npf.c use some map array accessing wrappers instead of direct access.
* Codechange/Fix: Named every enum in tile.h. Fixes a nasty bug on MSVC where arrays would be initialised with zeroes (tnx Asterix_)
* Removed magic numbers from tables in tile.c.
* Added some explicit casts in tile.h.

(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.