Crusher Direction Forcing + Detection radii

[Alasdairbugs]

For Horizontal crushers (normal), and to an extent, big ones:

• you have to be a little over half, and for the big crushers, a little over a third of the way to "call" the crusher to move horizontally in a certain direction
• this is too low of a radius. it should be exactly half, from where tux is most on a certain side of the crusher
• additionally, crushers that are only be able to be "called" to one direction, i.e., right, because there is a wall, i.e, on the left, then simply standing on the crusher at any point on the surface should activate it to move in the only direction it can