Added Nuggets::RDF::Turtle.
Redesigned Nuggets::Midos.

* Renamed Parser to Reader.
* Streaming interfaces for both Reader and Writer.
* Basic support for Midos Thesaurus output.
lib/nuggets/cli.rb (run): Added interface method.
Use `key?' instead of `has_key?'.
Added Array#hashify.
v0.9.7