GUI code cleanup

- Remove usage of std::numeric_limits<int>::max() in GUI which bring
unwanted behavior.
- Put the PixelShift options in a Gtk::Frame (requested on IRC)
- Add the fast_export raw options to the GUI (was created but not added
to the container). Incidentally, fix a memory leak.
- Add a missing History message

rtgui/bayerprocess.h

@@ -39,7 +39,7 @@ protected:
     CheckBox* dcbEnhance;
     Gtk::VBox *lmmseOptions;
     Adjuster* lmmseIterations;
-    Gtk::VBox *pixelShiftFrame;
+    Gtk::Frame *pixelShiftFrame;
     Gtk::VBox *pixelShiftOptions;
     MyComboBoxText* pixelShiftMotionMethod;
     MyComboBoxText* pixelShiftDemosaicMethod;