Short-term refactoring:
    - SSUSession:637, SSUSession:635 get rid of casting to SSUHeader
    - Identity.cpp:156 check for self asignment

Long-term refactoring:
    - Rely on a library for TLS and SSL.
    - Move parsing code out of networking code, to allow better testing. 
    - Separate front-end code (SAM, BOB, ...) from the back-end.


Additions:
    - Write tests.
    - Add documentation.