First pass implementation of ProjectGroups. Still need a way to retrieve
files in a given group.
Refactored ProjectGroup a bit, added RootProjectGroup class, and made
all Project subdirectories into groups. Added ability to get data in a
group and add data to a group, as well as get the full path to a group.
Implemented simple backup system for workbench.xmi so we don't lose our
Project list if the application closes unexpectedly and the
workbench.xmi is lost
ProjectGroup groundwork nearly finished, can serialize and deserialize
properly but file paths are not updated based on group.