Remove items from player when spectating

Closes #230

See merge request KartKrew/Kart!617

Disable bot controls after sprint map finish (resolves #260)

Closes #260

See merge request KartKrew/Kart!613

Make SPB match its target's hitlag

See merge request KartKrew/Kart!614

Add bouncing followers

See merge request KartKrew/Kart!611

Set `BobAmp` on a ground follower to set its bouncing velocity.

Player colour persistence (resolves #255).

Closes #255

See merge request KartKrew/Kart!610

An explanation for the approach: I started writing a whole system where an extra pflag would be defined for "colour is not currently the player's ACTUAL colour". Then I looked at the actual code flow that would be affected by it - the single line guarded by `if (forcereset)` - and decided it was simpler to just do an extra write in this once-per-player-per-frame function instead of increasing across-the-board complexity.

draw8 cleanup

See merge request KartKrew/Kart!598

Drastically simplified bot rubberbanding

See merge request KartKrew/Kart!604

Directional Lighting

See merge request KartKrew/Kart!608

Since your acceleration is tied to your top speed, we need to do this to ensure we're ONLY increasing the top speed, and not how fast they make it to that top speed.

- FULLY fix light offset still being applied on full bright walls
- Fix ceiling lighting being reversed

Minor Grow scale corrections

See merge request KartKrew/Kart!605

Fix blockmap WILD inconsistency when it's not PIT_CheckThing

See merge request KartKrew/Kart!601

Tester text

See merge request KartKrew/Kart!603

Eggman Mark cinder fix

See merge request KartKrew/Kart!600

(Sloped ceilings are reversed and not sure what to do about it)

Makes slopes at a great enough steepness able to match the contrast of walls.

COMING SOON: Directional lighting & contrast modifier, as options for map header.

Fake contrast setting is no more

Makes skyboxes look better

- Reorganized bot traversal
- Blocking line traversal includes tripwire
- Next waypoint detection uses blocking line trace now (this means bots can't sit outside of a tripwire wanting to go through it)

(The more this issue happens, the more we need to take the GZDoom approach of keeping this shit in a struct that you have to put in as a function argument, instead of global variable hellzone...)

These both require a couple loops to preform each, which probably adds up over multiple bots. Let's just precalculate them at the start of bot ticcmd.

Prevent rings from suddenly growing in size when a Grow player interacts with them, to match how using rings while grown or shrunk have them at mapobjectscale.