Added a method to extract the engine ID from the state ID
Added the BranchManager wrapper for Engine. It provides an IO for serializing/deserializing State messages into its own wrapper that supports states for which the parent is missing, and data structures for states present in this and other engines, as well as local and remote branch tips.
Added Javadoc to BranchManager
Renamed get to put; it really is a hybrid, but put better reflects its usage
moved some members around and added "sections"
added receiveUpdate stub with Javadoc
added receiveMissing stub with Javadoc
Implemented receiveUpdate & receiveMissing; added serialize and deserialize method stubs
Sending engine is properly added to received MetaStates now
Added methods and a callback interface for sending branch updated
Implemented serialize and deserialize
Added management of local branches
updating the current branch did advance the branch, but not apply the received actions
fixed an error that prevented updates from being sent
states sent by sendMissing are now marked as known by the receiver

testing in ticTacToe suggests it works!
Finish add-branches