Add LoadingControl

Moves LoadingBorder into its own control.
Projects can be marked as modified

When a project has unsaved changes, the program will reflect this.
Filter project flagging properties
Add project save confirmation on closing
Merge branch 'master' of github.com:IMDC/LiveDescribe-Desktop into valdev

Conflicts:
	LiveDescribe/LiveDescribe/View/MainWindow.xaml.cs