[Lukas] split get_contact into get_contacts and get_contact. get_contact_from_full_jid uses get_contact. Maybe could be merged with optional argument, but it's clearer this way. Fixes #3275

I will probably still patch a little sometimes.

and XEP-82 (dashes in timestamps).

Fixed a traceback.  Not sure how correct the contact=contact[0] is, but it handles the multiple return types from get_contact_from_full_jid

tab DnD)

 * Move checkbox to preferences. Fixes #2662
 * Merge option for muc and chat