Consider applying armor to all damage

[sprunk]

Right now armor is not applied to collision damage. This leads to surprising behaviour where units can still get damaged despite setting the multiplier to 0. I don't expect any game would mind since collision damage is very rare (ZK involves lots but we override it in a gadget anyway) but it would be good to ask beforehand.

spring/rts/Sim/Units/Unit.cpp

Lines 1298 to 1306 in 7363dbc

	if (!isCollision && baseDamage > 0.0f) {
	if (attacker != nullptr) {
	SetLastAttacker(attacker);
	// FIXME -- not the impulse direction?
	baseDamage *= GetFlankingDamageBonus((attacker->pos - pos).SafeNormalize());
	}
	baseDamage *= curArmorMultiple;