Typing API, Action ID, Event ordering changes
Apply most changes discussed in https://github.com/matrix-org/matrix-doc/pull/4#issuecomment-69751210
- Revert typing API to be like v1
- Revert Action IDs to be like Transaction IDs are for v1. Keep the echo down the event stream though.
- Add batching notes to some Action APIs and remove ordering by action ID.
Sessions still need to scrapped.
