Fixed stop method of ActiveObject

• removed code which hides exceptions within your statechart (this might unmask
  bugs in your design)
• changed how miros stops active objects.
  • a call to the ActiveObject stop method will not stop the active fabric
  • a call to the ActiveObject stop method will kill all slave threads which
    are posting events into that ActiveObject.
  • after the stop method is called on an ActiveObject, the ActiveFabric will
    not post events into that ActiveObject's input queue, since it won't exist
    anymore.
• removed unnecessary files from pip package (doc/test...)