Changeset 4640 for pjproject

Re #1708 (PyGUI: New Python GUI Application based on pjsua2+SWIG API)

Initial implementation, some account functionality has been implemented. Details:

• Uses Tk for GUI and pickle for object serialization. These are Python built-in modules
• So far so good, everything (=Account API only so far!) seems to work, including:
  • STL string
  • STL vector
  • inheritance
  • calling callback that is implemented in Python with inheritance (the "director" feature")
• Some notes though:
  • SIP worker threads need to be disabled because Tk GUI cannot be called from other threads (the worker thread will invoke callback which in turn will update GUI)
• Features implemented in the GUI so far:
  • Account addition/deletion/modification
  • Registration
  • Logging to window
  • Persistent config (limited)