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