Implement stub move and abort commands.

If configure SkySafari Plus v4.0 to tell it this is a Goto telescope
mount, then additional controls are offered like the left/right/up/down
buttons which appear while connected to the scope. These send the move
East/West/North/South command when pushed (Me/Mw/Mn/Ms) and the matching
abort slew command when released (Qe/Qw/Qn/Qs).

Since the iPad supports multiple touch, either East/West and North/South
can be used together to move the telescope on both axes at once.

Note that the mount type (Alt-Az versus Equatorial) does not alter the
movement controls - they are always East/West/North/South.
Implement stub set slew rate commands.
Stub entry for MS command, move to target