Merge tag '0.16.0' into develop

v0.16
Bugfix, typo
PEP8 fix
Removed unused import
Reformatted docstrings
Refactored
String the exception
Updated readme and changes
Merge branch 'develop' of github.com:ReactiveX/RxPY into develop
Bugfix. Should be append, not push
Removed unused import
Docstring changes
Bumped to rc6
Merge branch 'release/1.0.0rc6'