-Let SDL use its default ARGB layout when allocating a 32bpp surface and retreive from SDL_Surface::format. APART, RPART, GPART, and BPART are no longer hardcoded. Hopefully this should fix color issues on big-endian systems.

git-svn-id: http://odamex.net/svn/root/branches/rend32@4027 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Whoops, left out parentheses in r4027...

git-svn-id: http://odamex.net/svn/root/branches/rend32@4028 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Encapsulate the APART, RPART, GPART, and BPART functionality into DCanvas since the pixel format can vary for each DCanvas depending on bitdepth and fullscreen/windowed. The APART, RPART, GPART, and BPART macros are retained and access the respective accesor function for the global screen DCanvas object. 


git-svn-id: http://odamex.net/svn/root/branches/rend32@4030 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Merge from trunk into rend32.

git-svn-id: http://odamex.net/svn/root/branches/rend32@4031 b0bcef46-2027-0410-bd56-ab726e9a1d04