Be consistent with toaster's recent changes to copyright
- Fix flat DS_HOLES referencing incorrect background pixel - Add SPANDRAWFUNC_TILTEDTRANSSPLAT (fixes Lost Colony)
Two reasons: - Makes it more straight-forward to add brightmaps to the non-power-of-two rendering functions. - Made it easier to split off brightmap rendering. Hopefully improves performance, but I haven't thoroughly tested this.