(svn r4572) Remove vehicle_leave_tile_proc
There's exactly one implemented function (unbarring a level crossing) and one place where it can be triggered (a train leaves a level crossing)
It's a bit overkill, so just handle this one case where it can happen

(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 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 r815) Include strings.h only in the files which need it.
This should reduce the compile time after altering english.txt by about 1/3, because "only" 62 instead of 90 .c files must be recompiled.

(svn r724) Remove restriction that a tile can only accept 3 cargo types.
This especially enables houses to accept passengers, mail, goods AND food.
Add string templates for up to 5 cargo types for the tile info window. If more are needed just add them.
Simplify (de-uglify) the logic for cargo acceptence for houses and split the goods/food table into two. The acceptance is unmodified, but accepting goods AND food is now trivially possible. The exact amounts have to be decided.
This is based on Celestar's changes in the map branch plus some further bits that will be merged there soon.

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