Merge branch 'sofab194/pycommandcenter-master'

Following change description:

* Added getTarget() to Unit: (Accessed via unit.target in python)
  Returns target if unit has one, otherwise will fail the assertion (make
  sure not to call this unless certain that the unit has a target!).
* Added hasTarget() to Unit: (Accessed via unit.has_target in python)
  Returns true if unit has a valid target.
* Added isBlip() to Unit: (Accessed via unit.is_blip in python) Returns
  true if unit is a "blip" - a ping on the map.
* Added possible access to the current frame of the game in python
  (IDABot.current_frame).