Fix numerous nicksonline bugs

When nicks came online the nicksoffline signal was called, fixed.

Restored old functionality of first/second column for online
nick information.

Unlike previous nicksonline the netserver can now be set by WHO.
The only thing that isn't set then is the netserverinfo.
I think this largely eliminates the need to do a whois unless
the information is completely empty. (e.g. share no channels)
Allow filtering of the list with a search box
Include all server groups in edit notify dialog

Before only connected server groups were included, now all are.

Also made it so you can right click a server group to add nick
and that server group will be auto-filled in the edit notify diag.