BREAKING CHANGE: This changes the runInRoot method to not return a
future. As a user, if you need the result of an async computation passed
to runInRoot, please await it directly. Also the KeyVerification start
and a few call methods now return a future.
You can either set them to private on the client or overwrite the
behaviour for that on each readMarker call. This also handles incoming
thread receipts and tries its best to figure out what is the latest
receipt. This however breaks the old m.receipt account data event.