Make `MatrixEvent.event` contain the *encrypted* event, and keep the plaintext
payload in a separate `_clearEvent` property.
This achieves several aims:
* means that we have a record of the actual object which was received over
the wire, which can be shown by clients for 'view source'.
* makes sent and received encrypted MatrixEvents more consistent (previously
sent ones had `encryptedType` and `encryptedContent` properties, whereas
received ones threw away the ciphertext).
* Avoids having to make two MatrixEvents in the receive path, and copying
fields from one to the other.
*Hopefully* most clients have followed the advice given in the jsdoc of not
relying on MatrixEvent.event to get at events. If they haven't, I guess they'll
break in the face of encrypted events.
(The pushprocessor didn't follow this advice, so needed some tweaks.)
If an exception was thrown by the encryption process, the event would be
queued, but the exception would not be handled. This meant that the event got
stuck as a grey 'sending' event in the UI.
Fixing this correctly is slightly more complex than just handling the exception
correctly. A naive approach would mean that the event would be shown as a red
'unsent' message, and clicking 'resend' would then send the message *in the
clear*. Hence, move the encryption to _sendEvent, where it will be called again
when the event is resent.
Add a 'verified' property to the response from MatrixClient.listDeviceKeys, and
add MatrixClient.setDeviceVerified to set it. Also changes the format of data
stored for user devices in the session store slightly (in a
backwards-compatible way).
Use different mock http backends for the two different clients, so that we can
better control what each of them is doing (in particular, this is a
prerequisite for having them both running /sync loops)
The pyramid of doom was getting unmanageable, not to mention the difficulty of
diagnosing why tests were failing, so replace the callbacks with promises.
Fix a bug in the error handling in downloadKeys: If the http request failed,
then the exception would get silently swallowed and the promise would never
resolve.
Also: tests!
