Make parsing of Hello extensions more robust w/r to handling of unknown
certificate types
Add X.509 to list of supported client certificate types
Improve JavaDoc, adapt method names to better reflect their purpose, fix
indentation to use tabs instead of spaces
Fix negotiation of client and server certificate types to actually match
a client's preferred types with a list of types supported by the server
Merge pull request #22 from sophokles73/improvements

Improvements