wip reconnection
Fix regular expression for usernames

Occasionally you'll find a username that looks like

foo`!~foo@bar.com/blaz
Close new server window when connected
Scroll to bottom when switching tabs
Make some error messages more explicit
Finish reconnection feature

If you disconnect, it will attempt to reconnect with exponential
back off (up to a maximum of 60 seconds).

Now, if this was displayed in the UI somehow ... mmmmm.
Highlight tabs when messages are received for that channel

Need to work on a color scheme for when you are messaged.