Implement continuous tape labels and path-based label shapes.

- Added "roll" as a special paper id
- Added roll_width attribute to draw tape in previews
- Updated Brother QL-500/* label templates
- Preserve print dialog settings between print jobs.
- Added path based labels for arbitrary shaped labels.
- Fleshed out implementation of continuous labels.

glabels/SimplePreview.h

@@ -67,8 +67,7 @@ namespace glabels
 		/////////////////////////////////
 	private:
 		void update();
-		void clearScene();
-		void drawPaper( const model::Distance& pw, const model::Distance& ph );
+		void drawPaper();
 		void drawLabels();
 		void drawLabel( const model::Distance& x, const model::Distance& y, const QPainterPath& path );
 		void drawArrow();