Modify the TargetAbilityEvent interface.
Modify the TargetAbilityEvent interface.

Changes:
  * New Event.target_id and Event.target_type take the place of the
    previous Event.target field's components.
  * Event.target now is always a DataObject representing the target
    or None if no such object could be found.

NOTE: If the targetted object is behind fog of war the unit id will
not be available which creates a anonymous object of the specified
type. These units are not added to the replay.objects lookup table.

vlaufer/sc2reader,vlaufer/sc2reader,GraylinKim/sc2reader,ggtracker/sc2reader,ggtracker/sc2reader,StoicLoofah/sc2reader,StoicLoofah/sc2reader,GraylinKim/sc2reader