-Add templated drawing functions R_DrawColumnGeneric and R_DrawLevelSpanGeneric and R_DrawSlopedSpanGeneric with template parameters for the screen buffer data type (8bpp or 32bpp) and a functor that handles colormapping a source pixel to the screen buffer.
-This eliminates numerous extremely similar functions and encapsulates the differences in functors.

git-svn-id: http://odamex.net/svn/root/branches/rend32@3867 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Add parameters to the generic drawing template functions for the destination buffer and screen pitch.
-Add some comments and clean up a bit.

git-svn-id: http://odamex.net/svn/root/branches/rend32@3868 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Clean up R_RenderSegLoop1/2 and move dc_colormap calculations into R_SetColumnColormap.

git-svn-id: http://odamex.net/svn/root/branches/rend32@3869 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Begin work to commonize the solid & masked seg rendering functions.
-Add a common function R_RenderSegRange to handle drawing columns horizontally in interleaved blocks of four into a temporary buffer and then blitting to the screen. This contains the duplicated code from ZDoom 1.22's R_RenderSegLoop2 and R_RenderMaskedSegRange.

git-svn-id: http://odamex.net/svn/root/branches/rend32@3870 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Refactor high-resolution texture scaling and fix a bug where high-resolution midtextures were only visible from certain angles.

git-svn-id: http://odamex.net/svn/root/branches/rend32@3871 b0bcef46-2027-0410-bd56-ab726e9a1d04