Removed the extra set of quotes from string message constants.
Escape quotation marks in string constants.

I don't think removing the quotation marks is consistent with the spec,
but it isn't entirely clear.

Partially fixes #18
Added a link to the ROS msg language reference.
Ensure message type names are capitalized.

We ensure that we have a valid type name in one place.

Note that the only property we currently check is that the name is
capitalized. We should also check against a list of Haskell reserved
words.

Finishes fix for #18
Reorganized Topic-related code.
Reorganized ROS computation graph code.

This encompasses the Master/Slave APIs, the Parameter Server API, and,
eventually, the Services API.
Reorganized Node-related code.
Upgraded to latest binary package.

Addressed a deprecation warning associated with the binary upgrade.

Simplified various socket interactions with more consistent use of
strict ByteStrings.