Moved cocktailparty to examples. Its a bit more complicated than the other example but it does something cool though
Added another example: stack, as inspired by http://www.gamasutra.com/blogs/ChrisSimpson/20140717/221339/Behavior_trees_for_AI_How_they_work.php
Improved RepeatUntilFail by using children instead of decorated. Perhaps a distinction between decorators and composite state is handy
Added more docstrings
Added a Generator instead of Pop. Both can be useful of course