[Engine-XMPP] proper output for error messages
[Engine-XMPP, lib/agsxmpp] reset socket before reconnect
[Engine-XMPP] detect facebook and prevent facebook bugs
[Engine-XMPP] do not "update" PersonChat name if IdentityName didn't change

there is no update function for chats -> remove and recreate is not very nice, prevent it wherever possible
[Engine-XMPP] display "is now known as" message on IdentityName change
[Engine-XMPP] prevent duplicate printing of status update

some xmpp clients and servers create duplicate presence updates
[Engine-XMPP] don't print jids on facebook

facebook jids are basically meaningless to the user.
as the user cannot rename any contacts, there can't be much confusion about the contact's name
Merge pull request #63 from oli-obk/feature/more_agsxmpp