[Feature]: Second-life options for casuals

[jaj22]

Didn't implement any of these because I couldn't decide which to do, but maybe it's best to just implement more than one and let people choose. Options:

1. Some basic withstand system. Press button, get revived. Would need to be capped to one per N minutes, or possibly require a trip back to the HQ box. Could do with some other penalty too, like extra sway (setCustomAimCoef). Maybe a bit of grey filter.

2. Using your AI recruits as extra lives by switching to them. Weaker than it sounds because if you take heavy fire they're usually dead already. Works best if you're down somewhere with broken pathfinding and they're just milling around underneath.