-Change the cache-friendly blocking algorithm in R_DrawColumnRange to use 64 byte wide blocks regardless of the video bitdepth.

git-svn-id: http://odamex.net/svn/root/branches/texmanager@4313 b0bcef46-2027-0410-bd56-ab726e9a1d04
-drawcolumn_t::pitch now stores the framebuffer pitch in terms of pixels rather than bytes. This eliminates one division per call to a column rendering function.

git-svn-id: http://odamex.net/svn/root/branches/texmanager@4314 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Ensure each row of the framebuffer is aligned to 64-byte boundary in memory.

git-svn-id: http://odamex.net/svn/root/branches/texmanager@4315 b0bcef46-2027-0410-bd56-ab726e9a1d04