clean up custom maps

[iznogod]

Remove guns etc

[noobjumper]

Arguments against this:

• It's against the mapper's map design intention.
• It removes content from the game. Caveats:
• Some weapons are abusable (ray guns, custom RPGs, gravity guns). This is a solvable problem via code.

[Yocairo]

@noobjumper this ticket is pretty much exactly for the last point you mentioned. but we will have to think about maybe removing all/most guns. CSS is pretty chill because there is no spamming of bullets.