states. Fix #2755.

So all the messages are grayed.

compute metacontact big brother by comparing them instead of computing an absolute score for each one. fixes #2781 and #2156

[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.