Contact contact)
Look up a Tpf.Persona by its TelepathyGLib.Contact.
If the TelepathyGLib.Account for the contact's TelepathyGLib.Connection is `null`, or if a
Tpf.PersonaStore can't be found for that account, `null` will be returned. Otherwise, if
a Tpf.Persona already exists for the given contact, that will be returned; if one doesn't
exist a new one will be created and returned. In this case, the Tpf.Persona will be added to
the PersonaStore associated with the account, and will be removed when `contact` is
destroyed.
| contact | the Telepathy contact of the persona |
| the persona associated with the contact, or `null` |
0.6.6