Python-engineio-v3

- workaround double utf-8 encode bug in javascript client [315](https://github.com/socketio/engine.io/issues/315) ([commit](https://github.com/miguelgrinberg/python-engineio/commit/00d2459fcc7d89c7f35a2b3734b339c0fc148b1f))
- upgrade to a more recent engineio.js for the examples ([commit](https://github.com/miguelgrinberg/python-engineio/commit/d61c3ac9d6abd0e0af4518bd6486ec5c218f3ba9))
- do not close a socket that is already closed [312](https://github.com/miguelgrinberg/Flask-SocketIO/issues/312) ([commit](https://github.com/miguelgrinberg/python-engineio/commit/ef20ffcf9abc074493501b284ef2289cfaf6417d))

- add __version__ to package ([commit](https://github.com/miguelgrinberg/python-engineio/commit/8e1f4e0b3cbfda8d1ac1dcae7102e9f1b3046c88))

- corrected logic that selects gevent_uwsgi as async mode [28](https://github.com/miguelgrinberg/python-engineio/issues/28) ([commit](https://github.com/miguelgrinberg/python-engineio/commit/db2fb14a252f0b142525d734bf60f665cb043367))
- documentation fixes ([commit](https://github.com/miguelgrinberg/python-engineio/commit/43fbe9a52e0a36c2cc73cf6e8064c55083c5ad61))

- updated Server class docstring ([commit](https://github.com/miguelgrinberg/python-engineio/commit/8b5304808bf62cd5215a4e75d1a3c97b07615ec9))
- added async_handlers option to server ([commit](https://github.com/miguelgrinberg/python-engineio/commit/c9133c2392baee13d7e3234d8aebfe550f106131))
- documentation for new gevent_uwsgi async_mode ([commit](https://github.com/miguelgrinberg/python-engineio/commit/3f0b4e3a5cb1f221702b4182c4dda7b91a1fdbd0))
- add unit test for complete code coverage ([commit](https://github.com/miguelgrinberg/python-engineio/commit/36bb48c66b3b54635f55c77cf7b54c9bbc006b84))
- Merge branch 'efficiosoft-uwsgi-gevent-support' ([commit](https://github.com/miguelgrinberg/python-engineio/commit/ad64b54be24e5df17b4e08150693997eb404c0f1))
- Added websocket support for uWSGI with gevent ([commit](https://github.com/miguelgrinberg/python-engineio/commit/8f92f4eba2f94d9388a98fadc38b95611a49056d)) (thanks **Robert Schindler**!)
- minor updates to readme file ([commit](https://github.com/miguelgrinberg/python-engineio/commit/298310af53f1e8bc87468d1b3ed1f146167c090a))

- minor comment additions to examples ([commit](https://github.com/miguelgrinberg/python-engineio/commit/c85d06ebb3c5414c2b6b28a900e0e6d5f1916dd5))
- async message events, sleep function, better client timeout Several improvements in this commit: 1. Message event handlers are invoked in a thread so that they are non-blocking. 2. Added a sleep function that is generic across async modes. 3. The timeout to declare a client gone has been extended to match the ping timeout setting. ([commit](https://github.com/miguelgrinberg/python-engineio/commit/6670627ea404679fc794b496c21ffce689fc6151))

- do not crash if recipient of a message is gone ([commit](https://github.com/miguelgrinberg/python-engineio/commit/95c9a55457e9cbd36597b14ad840e31abdb2030e))