LocationAnnotationNode labels are drawn using an offset above their location

[halmueller]

A LocationAnnotationNode does not appear on screen at the same spot as a LocationNode created with the same location. This appears to be intentional, caused by this line near the end of updatePositionAndScale(...):

    self.pivot = SCNMatrix4MakeTranslation(0, -1.1 * scale, 0)

I propose exposing that offset factor as a property on LocationAnnotationNode, to allow nodes to be drawn at their correct spatial location, or above it, or even below it. Call it labelYOffsetFactor.

I think it would be more intuitive to have a positive value of the property mean "up" than for it to mean "down". So the labelYOffsetFactor's default value would be 1.1, to allow current behavior. If I want no displacement, I'll set it to 0. If I want the label drawn below instead of above, I'll set it to -1.1.