* Make TIME part of HUD count down in a bunch of circumstances where it was otherwise some other seperate thing.
* Make race countdown happen in a bunch of appropriate circumstances.
* Refactor race countdown.
* Remove a lot of useless stuff from H&S/Tag UI.
* Make co-op/competition/race end-of-act countdown use the race countdown and bigger HUD font.
* Remove useless PLAYING/SPECTATE text from lives element.
* Merge lap counter into lives element.
* Move some other text around.

* Remove deprecated P_Random() from Lua.

* Clean up a lot of NiGHTS stuff still using the old, shitty NOSCALESTART offsetting in nonstandard resolutions.
* Clean up the ST_ drawing macro list.

* Fix Old Special Stage offsets.
* Fix drowning number offsets.
* Remove useless "WS" macros.

* Remove redundant check from V_DrawFadeScreen().
* Clean up potential endless sound source in Race HUD.

* Add a drawFill fallback for COLORMAP too.
* Correct a few index mishaps.

   - controllable strengths between 0-31 for COLORMAP lump like before
   - arbitrary colour indices in the palette via TRANSMAP lumps, with strengths 0-9
   - exposed to Lua as v.fadeScreen(color, strength)!
* Remove last vestiges of V_STATICPATCH.

Fix for "playdemo" not working with custom home paths

See merge request !221

Hotfix for "LUA PANIC" crash when joining a netgame

See merge request !222

General sky fixes

See merge request STJr/SRB2Internal!132

Fixed sky-sky thok barriers showing HOM (turns out the floor and ceiling share the same plane, so I've modified the code to account for this)

Additionally, place some optimisations in both software and OpenGL; in particular one has been added for when all of back and front sector (floor and ceiling) is sky: since everything is "open" anyway, we can simply the usual checks involved.

Thankfully it was really just a copy+paste of the code I already tinkered with for the normal ceiling sky based thok barriers, but tweaked for floors instead

Cleanup of the code I've tweaked for skies, added SLOPEPARAMS macro to R_StoreWallRange for use in getting seg end z positions

some cleanup of software's seg rendering code, moved Red's polyobject plane hack to R_StoreWallRange since it doesn't actually need to be done every column draw

(I suspect polyobject planes don't actually need the minx/maxx hacks anymore, but I haven't the time to test that tonight nor is this branch really suited for it anyway)

* Thok barriers with slopes now render fine in software
* The solid "sky walls" between different-height thok barriers adjacent to each other are gone. Forever.

(I'll get round to OpenGL later)

This potentially allows FOFs and polyobjects to display sky flats on them properly, unless skyboxes are involved in which case they'd fail either way

I also updated or added comments to some places of the sky drawing code and related where useful

Added a failure animation if you don't get the emerald. https://cdn.discordapp.com/attachments/402861856219463681/405477752972509185/srb20004.gif

* Make emeralds fall onto the end tally. https://cdn.discordapp.com/attachments/400761370800422922/405122775272128512/srb20003.gif

* Fix some mistakes in the comments for v_video.h.

* Completely redid how splitscreen works, with eventual support for quads. Squish per-player stuff automatically into the right places! Works in GL, associated flag kills V_SPLITSCREEN.
* Seriously update the lives-drawing function for all gametypes, with strings that replace the lives number whenever it's missing (deprecates SKINNAMEPADDING).
* Improved how the nosshack works, alongside many other refactorings.

* ArchiveTables: print an error if invalid key, to alert script author potentially
* UnArchiveTables: if the key is found to be nil after reading key and value, print an error and don't set them in the table

Prevent SV_SpawnPlayer from being able to freeze the game if gametic is 0. Additionally add a sanity check to prevent the loop going on more than necessary anyway

This commit fixes -playdemo and -timedemo params for command line, allowing them to actually work again

G_DoPlayDemo: prepend srb2home to the demo name (if an external file) so that demos in custom home paths can be loaded