TODO in no particular order.  Some of these will never be done.  There
are omissions of important but necessary things.  It is up to the
reader to fill in the blanks.

- Timeout failed watch responses
- Dynamic/supply nodes
- Persistant storage of introductions, watches and transactions, so daemon can restart
- Remove assumption that rename doesn't fail
- Multi-root transactions, for setting up front and back ends at same time.