New object oriented Python abstraction for pjsua API

[bennylp]

pjsua.py

Implement new objected oriented Python wrapper for pjsua API. This is a new Python module, and it is implemented purely in Python, on top of the C module.

_pjsua C python module

This is the implementation of the Python C module. It is based on the old py_pjsua.c module with some changes and new features. The py_pjsua.c module is now deprecated.

[bennylp]

Initial, alpha version in r2119

[bennylp]

r2120:

• updated setup.py for Linux

r2122:

• fixed bug in player_get_slot() and recorder_get_slot()

[bennylp]

In r2163:
Major modifications in Python module and pjsua.py wrapper:

• replaced call/acc/buddy dictionaries with user data attachment
• recommended to install callback when creating the object, to prevent missing some events
• fixed circular references by using weakref
• protect access to pjsua with mutex; found out that without this there will be deadlock in Python
• fixed memory leaks in the _pjsua.c module (objects reference counter not properly maintained)