Updated deprecated functions / make irkerd work as a library

Hi,

I made some small changes in irkerd so that it can be used as a library to create other irc clients.

My goal was to make a replacement script for irccat that handles SSL. I achieved that and wanted to contribute the changes I did to irkerd, if you'd be interested in them

I also did some updates to take into account deprecated libraries or functions in python3. I took care to commit each change independently to ease your reviewing. In one case I fixed an error: connections were not being closed when aborting irkerd by means of a control-C.

With these changes, irkerd still works as designed, a standalone daemon. But now, you can also import it and use it as part of your app. The next I had planned to do was to divide the irker script into two files, a libirker, and the irker app itself, which would include the library. Before attempting this I wanted to talk on #irker to gather feedback about this idea... however I don't see any community on #irker anymore so I just left it as is.

You can find the irccat client I wrote here (file is called irccat). This was a clone of the irker repo I put on my github while developing irccat. If you merge the changes, I'll remove my repository and just make it one for the single irccat script.

https://github.com/jkbzh/irccat

Thanks for all in advance.