-Merge from trunk into rend32.
-Change the new wipe drawing functions to be templated for either palindex_t (8bpp) or argb_t (32bpp) pixel types.

git-svn-id: http://odamex.net/svn/root/branches/rend32@3955 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Change the unrolled loop in R_DrawColumnGeneric to handle left over pixels after the loop rather than before.

git-svn-id: http://odamex.net/svn/root/branches/rend32@3956 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Columns in visplane_t::top now use viewheight to indicate that the visplane has no spans occupying that column. Previously, 0xFFFFFFFFu (unsigned) was used, which caused problems when casting visplane_t::top to a signed integer for rendering a range of columns for the sky.

git-svn-id: http://odamex.net/svn/root/branches/rend32@3957 b0bcef46-2027-0410-bd56-ab726e9a1d04