NOW this is good enough to ship

Hell Attack

See merge request KartKrew/Kart!35

New engine sounds by VAda

See merge request KartKrew/Kart!38

Karmegg

See merge request KartKrew/Kart!36

(I've moved the comebacktimer set into one level up from that conditional; don't worry, I checked - there's nowhere that accesses this field while you have bumpers, it's just always set here for some dastardly reason.)

Sal cleanup

See merge request KartKrew/Kart!23

Fix the mixed declaration and code warnings

See merge request KartKrew/Kart!37

 - Volume of your own engine is lower than default
 - Engine sounds get quieter with more people around, ala SMK. 16 player servers should hopefully not be loud as fuck :V
 - Starting countdown and drop dash revs up your engine now
 - Doubled sound distance

9 unique engine classes with 13 sounds each, which smoothly change. Each character sounds distinct now!

Noclip cam

See merge request KartKrew/Kart!32

Nuke a bunch of iteration things that have no purpose in SRB2Kart.

See merge request KartKrew/Kart!25

-skill launcher option

See merge request KartKrew/Kart!34

Fix the mixed declaration and code warnings that only don't appear currently because of a tiny Makefile issue.

# Conflicts:
#	src/p_inter.c

Frame Perfect Egg

See merge request KartKrew/Kart!31

Edit Pink, Navy, and Jet, add brown text

See merge request KartKrew/Kart!28

Droptweaks

See merge request KartKrew/Kart!27

Karma Eggman. Does what it says on the egg. Tried very hard not to merge conflict with `frameperfectegg`.

Also includes some adjustments to:
* Horizontal offset of Eggman countdown in splitscreen again. It's not perfectly centered either way, but on second thought I like this better.
* Sound of Lat`'s Mine/SPB explosions - now uses same sound as Karma bombing, instead of that shitty paraloop.
* Correctly wipe k_eggmanblame when it is appropriate to do so.

Also: temporarily cleaned up the M_CanShowLevelInList record attack conditions to automatically match what we want, instead of requiring us to apply a bunch of vanilla flags just to emulate our "available unless explicitly hidden" MP mechanism like is currently in maps.kart.

This function has caused me, so much unexpected pain because of just how out of the way it is, and NOTHING else uses it

(The code is slightly modified from what I put in bug-reports as a potential fix, but I'm glad I was on the right track.)

Move camera less often

See merge request KartKrew/Kart!30

Chat changes

See merge request KartKrew/Kart!26