Framing and unframing of messages for the wire protocol

Pretty simple little bit of code, really, but there it is.

Had a bug where I used size where I should have used paddedSize, but
testing caught it pretty quickly.
More and better networking code

This is slowly approaching becoming a real server...
Ignore reason for parse failure in RLP.decode

Right now I'm using Maybe as my general-purpose error type. This may not
be a great idea forever  -- it might be useful to carry more information
-- but either way I'd like to keep things consistent.
Handle a few corner cases in the RLP

These were mentioned in the yellow paper, but not the wiki, so I missed
them the first time around.