(svn r11005) -Codechange: move the tiletype specific terraforming checks to the functions for those tile types.
-Codechange: barren the rail grounds on terraforming.

(svn r10922) -Codechange: Allow building and removing tracks and signals when there is a
train on a parallel diagonal track that doesn't interact with this one. (frosch)

(svn r10659) -Codechange: updated documentation around RAIL_GROUND_FENCE_VERT[12] (frosch)
-Codechange: added documentation and SPR_ enums for track fences (frosch)

(svn r9371) -Feature: Add support for variable snow lines in the arctic climate, supplied
by newgrf files. When this is enabled forests cannot be built below the highest
snow line, and farms can't be built above it. Houses still use the
_opt.snow_line so they are all consistent, so to make them respect the snowline
you may want to use some newhouses features as well.

(svn r8876) -Fix

Replace tests with magic numbers by a simple extraction template for command parameters

(svn r8875) -Fix

Remove unnecessary EnsureNoVehicle() checks because they are
- pointless per se (f.e. there are no vehicles on house tiles)
- done again (f.e. using CMD_LANDSCAPE_CLEAR just a few lines later)

(svn r8841) -Fix

Remove {,u}intswap() and replace them by Swap()

(svn r8283) -Fix (r8128): Custom waypoint drawing used wrong bits since bitshuffling occurred. Also update with other station drawing changes (code duplication,
eh?)

(svn r8128) -Codechange: Split sprite and palette remap into separate 32 bit values.
This lets us increase the sprite width from 14 to up to 29 bits,
effectively nulling the old sprite limit. Table changes in next commit.