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.
Two notable consequences of this bug:
* The delay when pressing the item button as a spectator to toggle PF_WANTSTOJOIN was not present, leading to a rapid toggle and spurious changeteam commands.
* Lightsnaking through map hazards such as Lavender Shrine's stabbies caused you extra spicy unavoidable pain.
* When lightsnaking, update the camera angle at each waypoint step to prevent being dropped the wrong way around.
* The above bullet point is WIP. I've tried to restrict manual turning while lightsnaking, but it still happens and just gets yanked back at each waypoint. Would appreciate a bit of insight here.
* Fix HUD tracking for spectators by setting thiscam->chase each tic more definitively.
* Still happens for the very first tic of the map though, must be another data point I missed 😔
* Fix the vertical jittering when a spectator's camera is on the ground.
I really hated that one of your controls would just... turn off while you were flashing. Even if there was a very good reason to not allow it (Funky Kong's Ring Racers™️).
So instead, you CAN spindash in flashing ticks... but you're punished so harshly for it that it's not worth it. Which will actually teach people to not do it more than just the input arbitrarily not working :p
While in the air: release accelerate while at nearly-still speeds, and you'll preform a minisucle air drift boost. This mechanic is meant to fix the long-standing issue where you can get stuck in 0 speed in the air and not be able to do anything.
