Create a more generic ListTab class, and make MucListTab inherite from it
Add the /ad-hoc <jid> command to list commands of the given jid
Implement the execution of ad-hoc commands (#1832)
Fix two tb in the DataFormTab

- when list-multi doesn't have selected values at all
- text-multi.options() provided by sleekxmpp is apparently a '\n' separated
  string, and not a list
Remove a useless copyright notice
Make the inputs bigger in DataForm, to be able to see long values more easily
Do not beep in a MUC if we receive a message from one of our resources

happens when beep_on contains "message".

thanks eijebong