Add widget to edit terminal strip item layout

The widget is available in the project properties editor.
WIP

sources/ui/projectpropertiesdialog.h

@@ -32,7 +32,8 @@ class ProjectPropertiesDialog : public QObject {
 		enum Page {
 			Main    = 0,
 			Diagram = 1,
-			Autonum = 2
+            Autonum = 2,
+            TerminalStrip = 3
 		};
 
 		ProjectPropertiesDialog(QETProject *project, QWidget *parent = nullptr);