A variety of improvements.

Using VectorsMixin and DexAnalogMixin to compute grip force, load
force, cop etc in a consistent manner.

NB The source code for VectorsMixin and DexAnalogMixin reside in the VC
2010 directories (Useful and Grip, respectively) in anticipation of the
conversion to Visual C++ 2010.
Tidied up some GUI behaviour.
Squares instead of dots.

This might speed up refresh performance.