Spurious selection of stars causes erratic tracking

[bgottula]

In sensor fusion tracking mode, if the target grows too dim to be detected for a while the computer vision algorithm will select another bright thing that is the closest to the center of the camera frame. This can lead to some pretty erratic behavior. Investigate more robust strategies for filtering out objects that are not the target of interest.

One potential strategy is to reject targets that are more than some radius from the center of the camera if they do not appear in multiple frames near the same location. Stars and planets will appear to move as the telescope sweeps across the sky, but the target of interest should have very limited motion in the camera frame.