UI: make the layout scrollable when there are many buttons

src/layout_edit.h

@@ -1,6 +1,7 @@
 #ifndef QJOYPAD_LAYOUT_EDIT_H
 #define QJOYPAD_LAYOUT_EDIT_H
 
+#include <QScrollArea>
 #include <QStackedWidget>
 
 //for the tab list of joypads
@@ -33,6 +34,7 @@ class LayoutEdit : public QWidget {
         LayoutManager* lm;
 		//parts of the dialog:
         QVBoxLayout *mainLayout;
+        QScrollArea *padScroll;
         QStackedWidget *padStack;
         FlashRadioArray *joyButtons;
         QComboBox* cmbLayouts;