Bppy

This release focuses on the following:
* Adding priority-based event selection strategy (see [tic tac toe program example](bppy/examples/tic_tac_toe_priorities.py)).
* Creating an initial [documentation](http://bppy.readthedocs.io/).
* Manual b-program run with dynamic b-thread adding bug fix.

This release focuses adds external events support with some additional minor bug fixes (Thanks adielashrov).
an example for using external events [bppy/examples/external_events.py](bppy/examples/external_events.py)
*external events are not supported for solver based event selection strategy.

This release adds the ability to dynamically add b-threads during b-program execution (Thanks to maor226 ).
Examples of using this new feature can be found in the following files:
- [bppy/examples/hot_cold_dynamic.py](bppy/examples/hot_cold_dynamic.py)
- [bppy/examples/exponential_growth.py](bppy/examples/exponential_growth.py)

Initial release