Python-socketio

- unit test reorganization ([commit](https://github.com/miguelgrinberg/python-socketio/commit/b0a8b1f31bce4305c00ab0937ddfec1120a2d49d))
- user sessions ([commit](https://github.com/miguelgrinberg/python-socketio/commit/9f2186725adba33b634f7287e3518086e2bbc3ea))

- correct handling of disconnects [227](https://github.com/miguelgrinberg/python-socketio/issues/227) ([commit](https://github.com/miguelgrinberg/python-socketio/commit/45d880cf905f05e1c9966fbe46ed53236bda2851))

- SocketIO client
- reorganization of examples, plus some new ones for the client ([commit](https://github.com/miguelgrinberg/python-socketio/commit/4822d8125df11bbf2ef3061c0622164f37a261c9))
- minor example code fix ([commit](https://github.com/miguelgrinberg/python-socketio/commit/fc5fbcf005f750a67d6aeb7bbd190125ea7970fd))
- resolve wrong variable and css element [177](https://github.com/miguelgrinberg/python-socketio/issues/177) ([commit](https://github.com/miguelgrinberg/python-socketio/commit/251b5be9dfc5d88a3bbf146ff52197863d5ce109)) (thanks **iepngs**!)

- Fix variable referenced before assignment [85](https://github.com/miguelgrinberg/python-socketio/issues/85) ([commit](https://github.com/miguelgrinberg/python-socketio/commit/5b9b17c4a0654811aeda4184d159dafb5e0e4041))
- use Python 3.6 for docs build ([commit](https://github.com/miguelgrinberg/python-socketio/commit/142e4787375782c74d6d0b992115269dc290069b))

- update dependencies ([commit](https://github.com/miguelgrinberg/python-socketio/commit/f642a7f2078fc639ed1302b5b3f7133f19c629c6))

- fix backwards compatible problems with python-engineio 3.0 ([commit](https://github.com/miguelgrinberg/python-socketio/commit/fce2006eeef2528e9b59ce9097ff215e6117d787))