ApiKeyModel is no longer used in UserModel.
- Added FacilityModel and GroupModel.
- Added Facility Name field to Settings dialog, removed Institution field.
- Settings now stored in INI format, instead of SQLite.
- More sophisticated validation implemented for Settings.
- Added method to FoldersController for displaying message dialog from non-GUI thread.
- Added some returns to FoldersController to ensure that clean-up from exceptions is quick.
- Some minor refactoring.