Fix wiggle bugs

Ensure the wiggle percent is correctly saved in
UIView+InvalidWiggle, and that wiggles all take
place at the same time.
Add the cheat sheet to the gameboard

Add a cheat sheet to the gameboard. It has
an arrow to display and dismiss, and saves its
state in NSUserDefaults. It shows all combinations
of sets for the selected row and column
Add double tap to zoom out to the puzzle grid
Rename and update PuzzleCore submodule