Go back to dissing MessagePack and BSON since Jeroen pointed out some
limitations in the messagepack R package.  Remove citations to both,
and call them "not widely supported".

I think this wording is a fair compromise in that it still makes the
point I wanted to make that they address a shortcoming of text based
JSON for certain classes of applications by providing more efficient
binary encoding, but they make Jeroen's point that they still suck due
to lack of adoption and weak implementations for R packages so
shouldn't really be held up on the same level as JSON.

Add a paragraph break before we start talking about JSON, and merge
the binary json sentences into this new paragraph instead of being a
paragraph on their own.



git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rprotobuf@834 edb9625f-4e0d-4859-8d74-9fd3b1da38cb