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.

model/CMakeLists.txt

@@ -26,7 +26,9 @@ set (Model_sources
   FileUtil.cpp
   Frame.cpp
   FrameCd.cpp
+  FrameContinuous.cpp
   FrameEllipse.cpp
+  FramePath.cpp
   FrameRect.cpp
   FrameRound.cpp
   Handles.cpp