(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 r7198) -Codechange: Implement a circular tile search function.
Just provide the number of tiles per side, a pointer to a test function, the tile to start searching and voila.
Fixes [FS#364] by removing a lengthy and suboptimal random search pattern.
Thanks Rubidium.

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

(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 r3008) [ 1247535 ] Native Support for Win64 (compile&run only) (michi_cc)
Fix warning in graph_gui.c with const problem

(svn r2929) * Move DistanceTrack from map.c to npf.c and rename to NPFDistanceTrack.
* Make NPFDistanceTrack return the distance multiplied by NPF_TILE_LENGTH to prevent rounding
This should make ship and train pathfinding more accurate and faster.
* Update IsEndOfLine to prevent trains from trying to go off a slope onto a tunnel entrance.

(svn r2560) Fix: various minor code changes.
Added RandomTile/RandomTileSeed functions to generate a random tile.
Changed landscape routines so they don't assume that the Y map side is a power of two. (support for this is not complete, though)
Changed some frequently used map macros to not compute the values each time.
Silence some warnings on MSVC.

(svn r2181) - Add: DistanceTrack() to calculate the distance over optimally laid out tracks.
- Codechange: [NPF] Removed unused heuristic function NPFCalcTileHeuristic().
- Codechange: [NPF] Use DistanceTrack() instead of DistanceManhattan() for ship and train heuristic.
- Codechange: Renamed variables x and y to dx and dy in some of the distance calculation functions.

(svn r1751) - Feature: New PathFinder (NPF).
- Supports trains, road vehicles and ships.
- Uses A* pathfinding (same codebase as the new ai).
- Currently unlimited search depth, so might perform badly on large maps/networks (especially ships).
- Will always find a route if there is one.
- Allows custom penalties for obstacles to be set in openttd.cfg (npf_ values).
- With NPF enabled, ships can have orders that are very far apart. Be careful, this will break (ships get lost) when the old pathfinder is used again.
- Feature: Disabling 90 degree turns for trains and ships.
- Requires NPF to be enabled.
- Ships and trains can no longer make weird 90 degree turns on tile borders.
- Codechange: Removed table/directions.h.
- table/directions.h contained ugly static tables but was included more than once. The tables, along with a few new ones are in npf.[ch] now. Better suggestions for a location?
- Fix: Binary heap in queue.c did not allocate enough space, resulting in a segfault.
- Codechange: Rewritten FindFirstBit2x64, added KillFirstBit2x64.
- Codechange: Introduced constant INVALID_TILE, to replace the usage of 0 as an invalid tile. Also replaces TILE_WRAPPED.
- Codechange: Moved TileAddWrap() to map.[ch]
- Add TileIndexDiffCByDir(), TileIndexDiffCByDir().
- Codechange: Moved IsTrainStationTile() to station.h
- Add: IsRoadStationTile() and GetRoadStationDir().

(svn r1706) Implement ScaleByMapSize() and ScaleByMapSize1D()
These scale a number relative to the map size/circumference.
Use them to scale the amount of map objects.
Of course at the moment they return just the input, because there are no bigger/smaller maps yet.

(svn r1449) -Fix: signed/unsigned error on windows
-Change: Makefile added -Wsign-compare flag

(svn r1415) Move TILE_FROM_XY and TILE_XY to map.h and push TILE_[XY] bits from map.h into map.c.
Now the whole source except map.c is independent of TILE_[XY]_BITS!

(svn r1386) Move TileIndexDiff to map.h
Move _tileoffs_by_dir to map.[ch] and encapsulate it in TileOffsByDir()

(svn r1288) -Codechange: changed _map2 to an uint16. It is still saved and loaded as
an uint8 till the savegame version is bumped to version 5. Then it works
automaticly as a fully uint16. So _stations[] can not be increased till
after the bump!!