These cannot be done with the regular textures so there needs to be an option to create more than one native texture per FTexture. For completeness' sake there is also the option now to create a paletted version of a texture if the regular one is true color. This fixes a long standing problem that translations were not applied to non-paletted textures.
I have no idea why they were even in there, as they intentionally circumvented all GC related features - they declared themselves fixed if prone to getting collected, they all used OF_YesReallyDelete when destroying themselves and they never used any of the object creation or RTTI features, aside from a single assert in V_Init2.
Essentially they were a drag on the system and OF_YesReallyDelete was effectively added just to deal with the canvases which were DObjects but not supposed to behave like them in the first place.
Currently this is only being used for draw operations that are not automap related, i.e. DrawLine, DrawPixel and FillSimplePoly are not subjected to it.
This has increasingly become an obstacle with the hardware renderer, so now the values are being stored as plain data in the sector, with the software renderer getting the actual color tables when needed. While this is a bit slower than storing the pregenerated colormap, in realistic situations the added time is mostly negligible in the microseconds range.
