This implements a new socket option at global level NN_PARSE_PIPE_TYPE,

suggesting whether NN_PIPE_PARSED will be used for messages on the socket.

This API is proposed to solve the problem described on the mailing list here: http://www.freelists.org/post/nanomsg/header-behavior-for-ipc-vs-inproc,2

Signed-off-by: Drew Crawford <drew@sealedabstract.com>