Socketify

What is changed in socketify:

- fix WS upgrade when using SSL
- fix `res.write_offset`
- added `res.close()`

What is changed in socketify:

- `res.send` optimizations

10% to 25% faster in CPython3 and 8% to 13% faster in PyPy3

What is changed in socketify:

- fix NGINX default proxy with HTTP 1.0

What is changed in socketify:

- ws.clone() fix

What is changed in socketify:

- HTTPS fixes

What is changed in socketify:

- add `instance = ws.clone()` function

This enables the user to use the returned value of the clone outside any event methods, but the user should not try to use a closed connection.