Update for new smtk::project implementation
Updates this plugin to work with the project changes recently made to smtk.
- Adds "ACE3P" menu replacing the now-obsolete project-manager plugin.
- Adds operations Create, Export, Read, Write
- Subclasses smtk::project::Project class; adds string properties to store metadata (for now)
- Uses new pqLocationPlugin to locate the simulation-workflows directory
- Removes the "project save as" menu because it is not reliable
- Sundry bug fixes