Refactor roi point

This is only relevant to follow-me right now.  ROI points and guided points are two different things, and should be treated as such.  This creates a new class for ROIPoints.

Also,
- Makes ROI point 1m above zero altitude.  This means the gimbal will point at the person's face, not their hand or pocket (wherever the phone may be).
- Only sends new guidedpoints when location accuracy is less than 10m.  Safety Feature.