* Doc: Several new sections in the user manual, and start documenting the internals.
* S4U: Direct comms from host to host, without mailboxes.
* Many internal cleanups and refactoring to prepare the future.
* Doc: Several new sections in the user manual, and start documenting the internals.
* S4U: Direct comms from host to host, without mailboxes.
* Many internal cleanups and refactoring to prepare the future.