Implement the X:Line commands

This PR implements the following commands:
- KLINE
- GLINE
- ZLINE
- ELINE
- QLINE

With the exception of server to server support (which I'll get on once this is reviewed) they are fully functional. I did run into a slight problem with the ZLINE command, where if a Z:Lined user connects, it disconnects them with a broken pipe rather than the actual ban reason. I'm not quite sure how to work around this issue.
This is probably not the best way to do this; later, if the return value needs changed, we'll have to also remember to change this, and we'll 99-100% not do it, at least at first.

This is probably best done with a key check, e.g. `if "reason" not in data`.