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.
It's probably better to set the variable `duration` to `linedata["duration"]` before this line.  In the worst case scenario, if Python optimizes the second dictionary item reference out anyway, you've made the code ever so slightly more readable.