* Use asyncio lock when checking camera status
get_camera_status() can be called during normal autotracking movement and from routine camera_maintenance(). Some cameras cause one of the status calls to hang, which then subsequently hangs autotracking. A lock serializes access and prevents the hang.
* use while loop in camera_maintenance for status check
some cameras seem to take a little bit to update their status, don't assume the first call shows the motor has stopped
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