(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 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 r2868) Change the way NewGRFs are loaded: The loading process i no longer bolted onto the normal graphics loading.
This has two major advantages:
- Removal of a maze of global variables and distinction of cases from the sprite loading routines, which weren't directly related to the loading process in the first place
- NewGRF actions no longer occupy sprite slots - for example when using DBSetXL this saves about 2000 slots! (you could regard this as a bug fix)
If i didn't make a major mistake this change should have no negative effect on NewGRF support, please test!

(svn r2866) Move all functions and tables which aren't directly involved in managing the sprite heap to a new file gfxinit.c.
This doesn't ease the global variable mess, but makes the distinction between sprite heap and gfx loading routines easier.

(svn r2847) Don't remember the size of sprites during initialisation. Since the sprite loading was altered this is no longer necessary.
While here remove another write-only variable (_spritecache_size) and fix a comment (sprite replaces a lowercase letter instead of uppercase)

(svn r2845) Remove sprite size caching, it was unused
This makes GetSpriteDimension() superflous, because now it's just a thin wrapper around GetSprite() returning only part of the information, therefore remove it too

(svn r2833) Remove saving of sprite cache data:
the benefits are questionable, it's error prone, undocumented and hasn't been widely used for ages, if ever

(svn r2764) -Feature: Clone vehicles
-This allows a player to clone an excisting vehicle of his own
-[fix]: this uncovered an excisting bug in CmdBuildRailVehicle() where depots could build trains of the wrong track type. This is fixed
-Thanks to Celestar for drawing the sprites and _luca_ for including them in openttd.grf

(svn r2702) -Codechange: Cleaned up the sprite code and replaced many magic numbers
by enums. There remains work in gfx.c to move the "transparency" and
"recolor" bits around to make space for more sprites. However, 2800
additional sprites can now be loaded. There also remains cleanup and
Doxygen work on many of the header files.

(svn r1882) Add a basic check if a non-existent sprite gets accessed.
Now ottd bails out with an error message instead of segfaulting.
This is far from perfect, some checks after loading a savegame should be added.

(svn r1852) Start cleaning up sprite handling:
- Complement the sprite header struct with a variable sized array for the sprite data and rename it to Sprite.
- Use the correct type Sprite* instead of casting all the time (this causes some "assignment from incompatible pointer type" warnings, nothing serious, will be resolved soon)

(svn r1571) Feature: Visually enhanced autorail placing
When using the autorail tool, the rail pieces which are going to be build are highlighted.
If a piece is shown in red, this indicates that the slope/rail combination is impossible. It does not tell you if the rail line construction might not be possible because of other obstacles, e.g. houses or water.

(svn r1453) Feature: MD5 hash check for TTD files
The original TTD files are now checked with a MD5 sum to determine which version of the grf files is used and to warn about possible file corruptions. (Thanks to ledow for the original patch)

(svn r1343) -Fix: [Graphic] Autorail icon is now correct (Darkvater)
-Fix: [Graphic] Added resize icon (tnx tokai)

(svn r1038) Feature: OpenTTD runs with the grf files of the DOS version
Please read the Readme for further information. There are some minor graphical glitches when you use the DOS files. E.g. the autorail button is a bit screwed up.

(svn r803) Switch to ISO 8859-15
It has proper support for the euro sign and includes letters which are needed by the Latvian translation (and perhaps others), though the letter sprites are missing.

(svn r651) LoadNewGrfFile() now doesn't care about num_sprites and just loads whatever is
available. Fixes George's long vehicles. (pasky)

(svn r624) Merge r377 to trunk:
Remove the memmove special case for MSVC
According to the MSDN it was just plain wrong and memmove was directly used in some places anyway

(svn r607) -Patch: [ 985102 ] static cleanup
Thanks to lvoge

(svn r75) -Add proper crediting to graphics artists to about box.
-Change DEBUG lvl for GRF warnings/errors to 2, lvl 1 is used for copyright notices
-Fix show currect filename when debugging grf files