(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 r7523) -Feature: Add the possibility to change the newgrf configuration of a running game.
This is only possible in SP (or in the intro menu). During game play you will
get a confirmation window when applying the changes as some actions can crash
OpenTTD and/or make your current game unplayable.

(svn r4546) - NewGRF: add support for Action 0x05, type 0x04: replacement signal graphics. Thanks to Purno for supplying data to test
with.

(svn r3167) - NewGRF: Start moving custom station code to separate files.
Rewrite handling of station classes.
Allow for more than 8 station tile layouts.
Start of code to unload custom stations.

(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!