Added is.mapvizier function to test if object is of class mapvizier and associated documentation.  Also updated documentation for mapvizier constructor adn fall_spring_me().
Added strands_plot() function and documentation.  Updated data/nweamap to include Classroom assignements. Updated NAMESPACE.
Merge branch 'chrishaid-strands_plot'

I'm doing this because there were some conflicts flagged by github.