This reverts commit 5ec44ba3, reversing
changes made to 4c5d69b7.

The worst part is you could've just saved the player userdata and accessed it
later anyway while player.mo is nil.

Spectates/kicks players who aren't making progress, does it even faster if they're going backwards.

This is fixes crashes in replays because splitscreen displayplayers are
initialized to INT32_MAX there.

Did not get to finish all refactoring or even compile this, I'll continue later

Expose some more Kart functions, freeplay and rankings bumpers are now hud stuff you can toggle, + experimental playercmd hook

This broke MKSC in a minor way if you skip a specific item set and then take the big cut... I'll let it go anyway since its an improvement everywhere else.

- cmd->driftturn exists now, for figuring out how far you're turning. Added to prevent analog sticks from being able to get drift sparks faster.
- Feather bounce strafing moved to use cmd->sidemove, which means it also supports analog now.
- Braking now waits a few tics for you to be stopped for a few tics before it lets you go in reverse, as per Sev's request.
- Removed a lot of unused/redundant/commented out control code, and reorganized some of the existing code.

- Look backward button works
- Increased default cam_speed, from 0.3 to 0.45. This is the highest
value that I think doesn't look overly stiff.
- Removed bobbing in first person
I was trying to do the camera angle thing that we've been talking about
for a while, but I can't get it to work well.

Since lap time will only ever be used locally, it makes more sense to
just use one variable instead of a player struct variable

- Record Attack replays now save best lap time
- Removed instances of NiGHTS Attack
- Removed a lot of unlockable that have no use in Kart (ultimate mode,
perfect bonus, score emblems, etc)
- Removed all methods of activating ultimate mode

- Improve balloon-based items. Much more distinguished differences
between the different ranks
- Reverted Feather strafing. You can now just... properly move in the
air, if you're using a Feather or a Bounce Pad.
- Bounce pads are now stronger while using speed items.
- Fixed the long standing bug about offroad & ziplines working when
you're on FOFs above them. This is a tricky subject, so please report
any issues you may come across related to this.
- Shells should no longer travel to Mars, nor will they  when using
bounce pads. They should now do a gentle hop.
- :WIP: new MP Player Setup screen, now shows character stats. Will
later feature the list of characters in a row of icons, and a backported
2.2 color selector with toast's permission
- Renamed "Match" to "Battle" :p
- Yet MORE minor cases where kartspeed & kartweight were being read as
fixed_t when they're freakin' UINT8's, people!

Doesn't really belong in this branch but shut up! I'm lazy :p

- Comeback players are now 1 speed with -20 friction
- Bombing gives 2 karma now
- Item players should no longer be able to be hit
- Attempted to fix instances of trying to bomb someone while they can't
be touched causing you to lose all your karma and start a console
message saying you're back in the game, despite not rewarding a balloon
- Fixed a few places where kartspeed & kartweight were being read as
fixed point numbers, despite being UINT8's
- Fixed up kartstuff Lua support more, functions properly now

Set to mobj angle except when spinning where it's set to spin
Only 1 spin frame needed now

--------
Hardcoded Collide.lua.
Added player boolean array "Collide", used by Collide.lua.
Walls are now bouncy by default again, like they were in 1.09.
Buffed Orange Drift sparks, the boost now lasts 60 frames up from 40.

Friction updated. Added KARTSTUFF to lua. Added ->kartstuff to network syncing stuff (surprised it even worked before now???), also maybe items correctly reset at the end of level now.

(no actual SLOC changes)

The idea is for the layman Lua user to understand better what range of values to use for mobj types, states, sfxs, player #s etc. Additionally, mobjinfo/states/sfxinfo/hudinfo tables all now have actual bound checks when accessing/editing them. Yikes, why didn't they have any before?!

Fixes http://mb.srb2.org/showthread.php?t=41403. Not sure why nobody noticed this earlier.

Angles now go from 0 to 0xFFFF (360 degrees == FRACUNIT) instead
of using a full UINT32. Lua only has one number type, so signedness
gets in the way of using angle_t directly. This handling of angles
matches up with how ZDoom ACS scripting and the like does it.

I also changed all the integer casts and pushes of fixed_t to
their own macro in preperation for possible future seperation.