Now that we simply establish and save a session via SessionBuilder
rather than saving the keys to pass in during encrypt, we can stop
caching them in memory in between the identity key check and the
encryption step.
// FREEBIE
Fix bug where resending due to failed network connection would fail
silently.
Broken in 7b6820 refactor which changed arguments to transmitMessage
// FREEBIE
Fix a bad loop scope bug in getKeysForNumber by using forEach.
Refactor the initial process of establishing key material for devices
that do not have open sessions.
// FREEBIE
It's rare that we get in a state where we have a device record without a
session, but we should handle errors gracefully in that case. Catch them
and register them, except for identity key errors which are registered
in handleResult.
// FREEBIE
fixup error handling // FREEBIE
This function dynamically declares a bunch of functions which bind to
its input arguments. Instead, use a new prototypal class to define
these functions within the context of a particular message.
// FREEBIE
