dec encoding

[<aah@nofs.navy.mil>]

Chris suggested that encoding the axis will help
in positioning even with the slop.  It gets really
hard to program as you are attacking a moving target.
If you overshoot and decide you need to move a half-degree
back, then giving a stepper command for a half-degree
movement might result in no movement at all.  Then a
second command might move it too much, etc.  If the
motion is tight, then open-loop stepper movement works
just fine for the coarse positioning we need for the
4-degree field.
  So bottom line:  let Tom work on improving the
repeatability of the declination drive and removing
the slop.  Then we can consider other additions
if they are needed.
Arne