Values are subject to tweaking.
(AngleDelta stuff is a leftover of the previous attempt, but I think the code's useful so I kept it in this commit anyway)
All my work thus far on solving the drawflag/renderflag/additive/subtractive conundrum.
Outstandng problems:
* Bad additive/subtractive tables means that they appear opaque except under certain conditions.
* No support for FOFs, Polyobjects, or linedefs in OpenGL yet.
* All OpenGL support mostly done blind, may or may not function in practice.
If nothing else, the hard engineering problems are solved and it's just bug hammering...
* Introducing K_GetKartButtons(player_t), for adding false presses to.
* K_GetForwardMove(player_t) takes kickstarting into account, and is now applied to engine sound generation too.
* BT_REALACCELERATE has been deleted.
It's no secret that holding down a button a lot can fuck with your wrists and fingers. It's too late for me to be damageless, but I can at least create an option to reduce further harm.
This accessibility feature, when enabled (kickstartaccel and kickstartaccel2/3/4 in the console) behaves with the following properties:
* Hold accelerate for 1 second to lock it down.
* Press again to release.
* Short holds/presses do nothing (good for POSITION).
* Continue holding it during the releasing press to re-lock it.
* A small triangular UI element is added next to the speedometer sticker, which displays the current state of the acceleration kickstart for visual feedback. (NO SPLITS SUPPORT YET)
In addition:
* Add PF_ACCELDOWN and PF_BRAKEDOWN, and BT_REALACCELERATE (which ACCELDOWN tracks). Even if this feature never gets merged, BT_REALACCELERATE is required because sneakers and boosters force it on too (extending this is how I implemented it).
* Fix the dehacked playerflag list being out of shape.
* I replaced some existing flags during development of this branch, so their old uses have been whittled away.
* Becoming a spectator is now instant, and leaves no bumpable corpse behind.
* Players will now FAULT if they:
* change from a spectator into a player after the initial camera turnaround but before the end of POSITION.
* touch an instant kill FOF or get crushed during POSITION.
* become a spectator during POSITION. (I might change this later, seems overkill)
* If you respawn during POSITION, the jingle will not restart from the beginning.
* Change the FAULT animation to match spinout/currents.
* Clean up some of the spawning code to not place spectators on the ground.
