* Store the number of frames per sprite2 run in the spr2frames struct.
* Reintroduce P_GetModelSprite2, to allow for the sprite2 defaulting system to be used to full advantage even in GL.
* Instead of splitting the SUPER and normal SPR2 stuff within the same cell of the struct, have them exist in different cells just like in the "normal" sprite2 structs.
* Allow for just providing spr2 frames in order without specifying which "normal" sprite2 frame it's supposed to replace.
Also:
* Fix FF_VERTICALFLIP-ignoring regression.
* Fix whitespace adjustment in win_dll.c
* Remove bracket in P_GetSkinSprite2 because I realised it was extraneous while making sure P_GetModelSprite2 worked with it.
* Disable lives when Metal recording (and have a big flashing REC instead, because I'm a riot).
* Correct some minor directionchar issues (some introduced in this branch, some not).
* Tweaked to use new sprites.
* Jet fume behaves much closer to Lach's wonderful work.
* Instead of clobbering tracer to spawn powerup overlay, use hprev.
* Change timings. One second less to charge up, but two seconds less to spin them out.
* Remove terrible pinch overlay in favour of new dashmode-mimic flashing.
* Add an alternate DEMOMARKER for ending the Metal Recording on death, which kills the Metal object as well.
* Add some more relevant exceptions to the "most objects are removed when touching a deathpit" thing, primarily for the sake of ghosts and Metal playback.
* Add height changes to demos and Metal playback (to properly place thok aura relative to object).
* Fix followmobj recordings in reverse gravity (done via more strenuous flag setting + info height serialisation).
* Make RA ghosts fade in from start tic, and go colorized on their final one.
* Fix thok auras potentially doing bad things if they're set to MT_NULL.
* Add sprite change support to Metal playback.
* Re-enable some stuff I previously disabled for Metal recording/playback.
* Make ALL objects spawned with skins properly acknowledge that their spawnstate's frame is a sprite2, rather than just specific objects.
* Fix placement of Metal Sonic fume in reverse gravity.
* Since not backwards compatible with the previous test build, increment DEMOVERSION again. (Don't worry, we've got like 65524 more versions allowed before we run out of possible DEMOVERSIONs...)
