Added network stack overview.
Set up basic networking code.
Merge branch 'master' into networking
Early version of data link serial communication implemented.
Merge branch 'master' into networking
Implemented basic serial protocol.
Improved test and fixed issue when packing frames.
Merge branch 'master' into networking
Fixed.
Modified frame polling algorithm.
Basic implementation of network layer and simple echo service.
Cleanup.
Minor changes.