Celestron GPS driver isn't disabling tracking while slewing, causes trouble with CPC mounts.

[bobrich]

Describe the bug I have a Celestron CPC 1100 and find that if I slew the scope (typ using kstars mount control) with tracking enabled, the tracking will get interrupted for 5-10 seconds and throw off alignment.

Celestron doc here suggests tracking should be disabled while slewing:

https://s3.amazonaws.com/celestron-site-support-files/support_files/1154108406_nexstarcommprot.pdf

Note: in most configurations, issuing the slew commands will override (or conflict with) the tracking mode of the mount. Hence it is always best to disable tracking first using the Tracking Commands, issue the slew command, then re-enable tracking.

FWIW this appears to be largely addressed in 3rdparty indi_celestron_aux. It looks like it uses TrackState = SCOPE_SLEWING plus some additional info (ScopeStatus and axis state) and doesn't appear to be affected by this issue. Tracking isn't impacted by manual slewing.

To Reproduce

1. Configure KStars to control a CPC1100 mount with indi_celestron_gps.
2. Align the scope with the hand controller
3. Use KStars mount control to slew left, right, up and down
4. Observe that tracking is partially or completely stalled for 5-10 seconds

Expected behavior Slewing does not interfere with tracking.