Mostly rewrote the parsing logic to support incremental parsing and
to support parsing of client messages. Though I did not add events
for client messages, that's easy to add later.
Parsing now stops for both client and server if either encounters
any parsing error or invalid state.
After a complete handshake, server messages are no longer parsed.
Support for that is incomplete and not sure it's that useful anyway
since it mostly contains pixel data.
