-Fix sky2 and line special sky transfers.

git-svn-id: http://odamex.net/svn/root/branches/texmanager@3966 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Flats can now be rendered on walls.
-Remove the textures, textureheight, texturewidthmask, etc arrays from r_data.cpp since that information is encapsulated in TextureManager now.
-Added a specialized version R_RenderColumnRange that takes an array of byte* as the pixel source rather than an array of tallpost_t*. This is used for walls and the sky for now.
-Temporarily disabled masked seg rendering.

git-svn-id: http://odamex.net/svn/root/branches/texmanager@3967 b0bcef46-2027-0410-bd56-ab726e9a1d04