[ptx] a few remaining hitches

[Philippe Gac]

Hi Pablo,

thanks for the new snapshot that brings in still more convenience of use.

200% zoom is now working nicely (and is quite useful)

there is still a bug that causes a "Hugin fatal error" that appears sometimes: when you add a point, it seem as if
another hugin thread that searches for a matching correspondent doesn't let enough time so it be registered. Then when
you key in "Add", there would be no first point and a fatal error is raised. But, if you click again to re-create the
first point, it's OK.

I understand it's no time for big changes but may I venture a few idea perhaps easy to implement?
- correlation as a distinct, permanent field
- shift-click forces selection of a point of an already existing pair, zooming both panes around it
- points be ordered in CPs-panes view according to distance
- points be ordered in CPs-panes or CP-list views according to distance from the center of the image
- make all images independent for all parameters with one click

best regards

philippe