Merge pull request #1 from openwebwork/master

Update whwheeler's fork from the official base
Merge branch 'develop' of https://github.com/whwheel/pg into develop
Merge branch 'develop' of https://github.com/whwheel/pg into develop
Revisions to support both SVG graphics and file graphics
in the WWPlot system.  Also, a new graphics object Bar.pm
has been added for drawing bar charts.
Merge branch 'develop' of https://github.com/whwheel/pg into develop
Merge branch 'develop-trial' into develop