Changes included:
Warhead code split out of weapon code and refactored.
Warhead functionality now split into several classes, each handling one effect/impact.
Additional custom warheads can now be defined and called via yaml.
Custom warheads inherit the abstract class Warhead,
which provides target check functions.
Custom warheads have to define their own impact functions,
and can also define their own replacement for check
functions.
Weapons are now defined with the Armament trait
and turret parameters live in Turreted.
This has the side effect of allowing any number
and distribution of weapons and turrets.
