(svn r2635) Fix: [ntp/misc] Improve the old pathfinder. Changed it to A* instead of Dijkstra.
- Benchmark shows that NTP is now around 10x faster than NPF.
- Made IsTunnelTile macro to determine if a tile is a tunnel.
- Added some useful debugging functions for making tiles red / getting accurate timestamps.
- Remove old depot finding algorithm.
- Disable warning for signed/unsigned comparisons.

(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 r202) -Codechange: I missed some files with trailing spaces.. this should be
all ;)

(svn r160) -Codechange: made GetTileTrackStatus more readable (blathijs)
-Fix: some minor fixes around GetTileTrackStatus (blathijs)