* boards/gletters/README: added a comment explaining the fallrate and droprate are optional
	* boards/gletters/gletters.sv: provided by Göran Uddeborg <goeran at uddeborg.se>
	* src/boards/python/algorithm.py: changed the question mark color to black (for color blind
	and ease of view).
	* src/boards/python/anim.py: fixed a string.