Per Claude:
The key things the new comments add that the old ones were missing:
1. Palette RGB colors are completely ignored — only the index value is used as alpha. This is the non-obvious invariant that @notimaginative described.
2. Exact mapping table — makes the * 18 / * 17 math immediately readable, and clarifies the ANI vs PCX difference (> 15 clamps to opaque in ANI but transparent in PCX).
3. The broken-palette consequence — explicitly states that a reversed palette causes a white square, linking to #4148 so future readers understand the context.
FSO doesn't appear to use this any longer. And even when it was enabled the
requirements made it largely useless anyway. Removing to clean up cfile a
bit and so we don't have to keep maintaining it.
add -img2dds support
cleanup some D3D stuff (missing a lot since the old code is so unstable I couldn't get it working like I wanted)
some minor OGL cleanup and small performance changes
converge the various pcx_read_bitmap* functions into one
cleanup/rename/remove some cmdline options
Made some commandline variables fit the naming standard.
Changed timerbar system not to run pushes and pops if its not in use.
Put in a note about not uncommenting asserts.
Fixed up a lot of missing POP's on early returns?
Perhaps the motivation for Assert functionality getting commented out?
Fixed up some bad asserts.
Changed nebula poofs to render in 2D in htl, it makes it look how it used to in non htl. (neb.cpp,1248)
Before the poofs were creating a nasty stripe effect where they intersected with ships hulls.
Put in a special check for the signs of that D3D init bug I need to lock down.
Goober5000