-Column and span drawing functions now take a drawcolumn_t or drawspan_t parameter instead of using the dcol & dspan globals.
-Perform minor code cleanup.

git-svn-id: http://odamex.net/svn/root/branches/texmanager@4248 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Rename R_RenderColumnRange to R_DrawColumnRange and move it to r_draw.cpp. Instead of calculating the colormap for each column, R_DrawColumnRange takes an array parameter to indicate which colormap each column should use.

git-svn-id: http://odamex.net/svn/root/branches/texmanager@4249 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Recalculate the fixed colormap table when the camera's colormap changes.
-Fix colormap issue with skies introduced r4249.

git-svn-id: http://odamex.net/svn/root/branches/texmanager@4250 b0bcef46-2027-0410-bd56-ab726e9a1d04