MapObject & MonsterSpawnArea can be activated/deactivated using theisActive boolean.

No handle exist yet to deactivate these areas.
Deactivated areas are never returned by PredefinedMap API.
Inactive container areas' Loot are not created on
createAllContainerLoot() calls. Think of creating it on area activation
when implemented (TODO label placed in the code to never forget :p)
Updated comment; fixed old, one-object processing to better match the
List type.
Merge branch 'activable_map_objects'