Add option to play on bottom screen

[spellboundtriangle]

Some people have a GB Macro (or otherwise broken top screen), or just prefer playing on the bottom screen, so it would be nice if it were an option. It could be done through a button combo, ig

[AngelTomkins]

This shouldn't be too hard to change by calling lcdMainOnBottom() and lcdMainOnTop() to switch between the two screens. Though it probably would be best to setup a settings menu for changing things like this. I don't think this is high priority though.