-- Added support for terms with multiple assertions.
-- Can produce a Gexf file from multiple terms.
-- Added 'merge' method to combine terms with the same
value.
-- Added GexfExporter, to produce a Gexf file from all
(k,v) pairs of parsed sentences in a Redis store.

Signed off by: Mark Farrell<markfarr2011@gmail.com>
-- Added the instantiable Environment class, facilitating the insertion,
joining, and selection of topics.
-- Accounted for cycles in the toGexf utility method in Environment.

Signed off by: Mark Farrell<markfarr2011@gmail.com>