Change the keys to rotate about tetris

[Arsenic-ATG]

I personally find using z and x for rotation much more convenient, but I still think, for most of the players, using up-arrow for hard drop doesn't come naturally to them.

maybe we can have these controls on top of the current controls we have.

key	Action
left_arrow	move left
right_arrow	move right
z or up-arrow	rotate clockwise
x or ctrl	rotate counter clockwise
up_arrow space	hard drop
down_arrow	soft drop
p	pause game

[ppitu]

In most tetris version which I play they use space as hard-drop and up-arrow as clockwise.

So for the player it's easier to start play with well-know combination of keys.