Add support for ~ and & as nickname prefixes

First off, I'd like to note that I did not test these patches, as I was unable to install Eclipse and my generated build.xml did not work. Although these patches are untested, I believe them to be safe to merge. However, please merge with caution if you decide to.

These patches should, assuming I understood your code correctly, help Yaaic correctly recognise ~ and & as nickname prefixes. These are not used by most IRC servers, but there are some that use them. I, for example, am a member of an IRC network which uses ~ for the channel creator. Whenever a channel creator disconnects, Yaaic does not recognise this and leaves said user in the nick list, giving a wrong image on who is online and who is not.

If you are looking for a server using these characters, GeekShed seems to be one, and they have their usage documented [here](http://www.geekshed.net/2009/10/nick-prefixes-explained/).

Thank you for your time and I hope this pull request will be useful for you.

Kind Regards,
Ruben van Os
(TheLastProject)