Implementation of screen rotation without use of additional layouts.

This is based on what was done using additional layouts, but modified
to have a variable to control rotation and making it so Single Screen
Layout behaves like Upright Single would, and Default Layout behaves
like Upright Double would, when the new variable is used.

Large Layout and Side Layout currently ignore the new variable.
New variable still currently doesn't have a hotkey.

src/core/settings.h

@@ -150,6 +150,7 @@ struct Values {
 
     LayoutOption layout_option;
     bool swap_screen;
+    bool upright_screen;
     bool custom_layout;
     u16 custom_top_left;
     u16 custom_top_top;