1) Since we're not CPU or space constrained (and are in fact
padding), and since keystream reuse would be more catastrophic
than IV reuse without chosen plaintext.
1) Break the core cryptography functions out into libaxolotol.
2) The objective for this code is a Java library that isn't
dependent on any Android functions. However, while the
code has been separated from any Android functionality,
it is still an 'android library project' because of the
JNI.
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.
