[CLOSED PR] Kinetics improvements & magazines

[TDHooligan]

Mmm, overall I don't personally see the need to de-abstract this - while the current implementation is, well, abstract and gamey, this is a video game (and even most shooters treat ammunition as just an invisible bucket of bullets that you shopvac out of corpses) and imo we're not really a game about guns to the extent that justifies realistic magazine handling etc.

fair nuff. if that's the consensus i'll rip out the mag changes & just push up the firemode stuff.

I will note there are a reasonable number of bugs owing to the weirdness/vagueness of how ammo is both magazines & loose ammo.
i could also disable the gameplay changes and keep magazines & bullet sprites, rather than a using the weird remove_on_empty bool.