#3 reporting pan, tilt, fov

[Bruno Postle]

If freepv reported the final pan, tilt and field of view to STDOUT on exit, then it could be used as the basis of a replacement for pteditor. ie:

1. Open an equirectangular image in freepv
2. Pan to area to retouch
3. Close
4. External tool extracts the view to a rectilinear file
5. User edits this view in an image editor
6. Tool reinserts the view into the equirectangular
7. Reopen the equirectangular in freepv