Snap to ground fix

Closes #165

See merge request STJr/SRB2Internal!274

MP/Old Special Stage ring stuff

See merge request STJr/SRB2Internal!276

New award rings linedef executor

See merge request STJr/SRB2Internal!263

Fix old Special Stage failure sounds not always playing

See merge request STJr/SRB2Internal!275

Titlemap Lua

See merge request STJr/SRB2Internal!270

Add rings to old/MP special stage HUD + make both them and spheres (in old special stage only) count down rather than up, to match s3k

Bustables and landing events

Closes #157 and #162

See merge request STJr/SRB2Internal!262

Spring angles and ring angles

See merge request STJr/SRB2Internal!266

Special stage related fixes

See merge request STJr/SRB2Internal!269

MANIASPHERES de-hardcode

See merge request STJr/SRB2Internal!268

Additional spring flags

See merge request STJr/SRB2Internal!256

Smiles tail scale

See merge request STJr/SRB2Internal!273

Diagonal spring ring fixes

See merge request STJr/SRB2Internal!267

Modify P_CheckSector with a modified version of Sal's attempted proper fix for polyobjects crushing, so that we only need to check the polyobject's control sector directly in the waypoints code.

This time I've definitely fixed that teleport to ground issue I'm pretty sure, I don't get it in my tests at least.

Add openfloorrover and openceilingrover vars so that PIT_CheckLine can update tmfloorrover and tmceilingrover properly via P_LineOpening

...which should hopefully stop that issue where you just teleport back to the ground. Assuming this works as expected.

Also this is untested lol.

Was reviewing old merge requests as a procrastination technique, and discovered that the followmobj's scale was being inaccurately handled for Smiles' tails! Fixed that...

# Conflicts:
#	src/p_user.c

* Strip the word "function" from INLEVEL error messages, since they're now shared between access and function cases.
* Move it into lua_script.h, so it's available to everything that needs it.

Fix lua scripts erroring on the title screen because they're run there but it's not counted as GS_LEVEL (aka #168).

* Fix something I neglected earlier when fixing Ghosts and Replays for 2.2 - the fact that the player's skin will change if they don't have NiGHTS sprites like Sonic does not being accomodated.

* Fix "exitlevel" being counted as a special stage success despite not giving you an emerald by inverting stagefailed's default value, since there's only a limited number of ways you can WIN at a special stage.
* Correct a potential source of desync in P_GiveEmerald.

Make MANIASPHERES' #define'd away stuff also recreatable with SOC, since I want to release it publically if the team don't want it.

* If a spring has vertical speed AND horizontal speed, always set the player's angle when touching it.
* If you have less than 32 rings and spill them, they now get launched away from the player's motion, rather than in the direction of the camera.