"Area" type attacks

[domob1812]

In addition to attacks with a single, auto-selected target, we should also implement attacks that affect all enemies in their range at once. For this, we should be able to mark attacks as area: true. Then instead of target finding, we just need to mark if there were any targets in range (so we can retrieve those attackers later on again). And when dealing damage, we simply run through all L1 targets again.

A single random roll for all of the affected enemies is fine, so that the attack is "consistent" in any single turn. (I.e. the randomness affects the attacker side, not the target side.)