1) In addition to the Recipient interface, there is now
RecipientDevice. A Recipient can have multiple corresponding
RecipientDevices. All addressing is done to a Recipient, but
crypto sessions and transport delivery are done to
RecipientDevice.
2) The Push transport handles the discovery and session setup
of additional Recipient devices.
3) Some internal rejiggering of Groups.
1) Refactor recipient class to support asynchronous loading operations.
2) Refactor recipient factory to simplify recipient access.
3) Consoliate everything into one recipient provider that is capable of
doing async lookups and intelligent caching.
1) Add >= ICS profile support (the system-supported "me" contact).
2) Improve <= Gingerbread support for me contact by auto-detecting
contacts that have the same number as the SIM card.
3) Tie in identity key import/export support to the "me" contact.
4) Don't display a "me" selection option in preference if it can
be auto-detected.
5) Refactor out the ContactAccessorNewApi back into the base class.
