Added a UnitZoneChange event that is fired whenever a unit's zone membership changes.
The unitsInZone output variable is now updated based on UnitZoneChange events.
The unitDaysInZone and animalDaysInZone output variables are now updated based on UnitZoneChange and Destruction events.
Merge branch 'master' into simpler-reporting
Merge branch 'master' into simpler-reporting