Reset font in main menu

[ghost]

The font should be reset to default when the Thumby main menu is loaded. Right now games can set a font and it will be used in the menu.

[ace-dent]

Really we should ensure all games (at least in the arcade) have a clean reset()... there's a lot more than font's that can be messed with!! ;-)
Does this happen on a real device or just Fast Execute / Emu?
I added these lines to protect from such issues:

TinyCircuits-Thumby-Code-Editor/ThumbyGames/main.py

Lines 24 to 25 in eb26c45

	finally:
	reset()

... So after exiting any launched game we do a machine.reset().