Work on client/server synchronization

Update TODO.md

Removed nm_playercommandreceived message; it wasn't strictly necessary
and its purpose has been subsumed by the overall sync design.

Servers now send all needed commands to each client in the
nm_playercommands message.

Update the tags
More work on sync

Try and use __func__ appropriately

Update tags
Still working on sync; currently chasing down delta creation problems