Fold and unfold

User can use the button in the tool bar or short cut key to fold and unfold the box template, the fold and unfold speed is adjustable at the same time.
M: Fold and unfold automatically, press twice to pause;
N: Rotate automatically, press twice to stop;
B: Fold, user need to continually press the key;
V: Unfold, user need to continually press the key.