Rename constants and use FIXED_TO_STRING

A preprocessor trick lets us easily convert compile-time constants into
strings. Make use of this.

Also rename most constants and shuffle them around a bit, into a more
logical order (on both counts).

Signed-off-by: Luke Stuyvenberg <stuyvenberg@wisc.edu>
Add StepSize to Twister (deg/step) & use

The Twister has not yet had a concept of step size; add this in and make
use of it in the Twister's movement command.

Additionally, alter the stage's CreateProperty call for step size, to make
it unalterable after initialization.

Signed-off-by: Luke Stuyvenberg <stuyvenberg@wisc.edu>
Remove XY Stage's GetOrientation

After removing the #if'd out parts of this code, the entire method
effectively became dead code. Moreover, its implementation was confusing.
The direction of movement is still curious, and will need to be
investigated, but that is for later.

Signed-off-by: Luke Stuyvenberg <stuyvenberg@wisc.edu>
Add min/max properties and use them

The stage, twister, and X/Y stage were inconsistent in their
implementation and use of min/max properties. I've added them where
missing, altered GetLimits to use them, and used them to bound movement in
the SetPosition methods.

Signed-off-by: Luke Stuyvenberg <stuyvenberg@wisc.edu>