I just pushed a new tag to the Matrix-Client repository and the features should be available in MELPA shortly.
I added HTML rendering of
org.matrix.custom.html matrix events which are used by Vector's markdown
feature, primarily. There is no support for sending HTML messages from this thing right now, I may
add that in the future.
Also new in this release is a connection watchdog; Previously, if you went offline, you would just silently be disconnected from the event stream. What's worse is that if you reconnected, you would still be able send messages that wouldn't echo back to you! The new feature starts a timer that runs at twice the rate of the maximum event stream timeout. what this means is that if you leave the default 30 second event stream call timeout intact, after 60 seconds the watchdog timer will run and see if there have been any callbacks from the event stream. If there have not been, it will attempt to re-connect the event stream and get you back online.
As always, let me know on Matrix or via email if you have issues with the release.