Endgame code refactor
This is mostly just some code cleanup and moving about:
* `Y_EndGame` was moved from from y_inter.c/h to g_game.c/h, and renamed to `G_EndGame`. Frankly the old place that function lived didn't make sense, since it has nothing to do with tally screens directly.
* Most of `Y_FollowIntermission`'s code was removed, because `G_AfterIntermission` does it all already.
* And lastly, `G_ExitLevel` uses `HU_ClearCEcho()` instead of `HU_CEcho("")` to clear CEchos from the screen.
The only visible changes in-game from the above should be just that log.txt stops adding empty new lines when you complete a level, and CEchos will always be cleared after tally screens when a level goes to credits/evaluation next.
See merge request !98
SDL fixes and cleanup
Mostly cleanup tbh. I noticed a few things that bugged me when examining SDL's code recently, thought I might as well fix them up a bit.
These changes definitely does not affect netplay, so this can be merged to master just fine.
See merge request !183
Nojumpspin fix
MI can attest to this being a problem that's now solved.
To test, check out root/!LatestSRB2Files/srb2win_branch_jumpfixes.exe and root/MonsterIestyn/robohood.wad.
See merge request !95
R_InitExtraColormaps fix
This fixes the `R_InitExtraColormaps` function so that it correctly realises there are no "extra colormaps" actually in SRB2's files, rather than telling you there are 6 extra colormaps on game startup (or however many WAD files total you have added).
For those who don't know what the function does, it searches for C_START/C_END markers, and if they exist, adds any lumps inbetween to a list of extra colormaps internally. They are never used by the game though, since we last supported colormaps of that kind so long ago I don't think anyone remembers when anymore (definitely more than a decade at least).
Merging to next since I don't know if this would cause any netplay issues or not tbh.
See merge request !182
This is just in case someone actually tries to dump in C_START/C_END and "add" colormaps using them, not that they would ever be used currently anyway.
Jet Jaw crash fix
Turns out not having MF_SHOOTABLE can cause the Jet Jaw to endlessly loop between the two states, until somehow LUA_CallAction inexplicably causes Z_StrDup to crash anyway (that one's a mystery to me, I'm not going to look into it right now). I tweaked A_JetJawChomp so this endless loop can't happen anymore.
See merge request !176
<Alam_Squeeze> p_floor.c:2932: warning: 'widthfactor' might be used uninitialized in this function
<Alam_Squeeze> p_floor.c:2932: warning: 'heightfactor' might be used uninitialized in this function
<Alam_Squeeze> m_menu.c:1907: error: initializer element is not constant
<Alam_Squeeze> m_menu.c:1907: error: (near initialization for `OP_ScreenshotOptionsDef.drawroutine')
<Alam_Squeeze> m_menu.c:9353: warning: 'M_DrawScreenshotMenu' defined but not used
<Alam_Squeeze> Makefile:770: recipe for target '../objs/Mingw/Debug/m_menu.o' failed
<Alam_Squeeze> make: *** [../objs/Mingw/Debug/m_menu.o] Error 1
