F3 CP display should be restricted, like the optimiser

[Pwomack]

When performing stepwise optimisation (sometimes needed in mosaic mode) one
would "obviously" set the "Only use control points between images selected in preview window",
and them perform an optimisatio after each image is added.

Having performed an optimisation, it is plausible that the optimisation
gives a good average and standard deviation, but has a high max.

This implies that some outlier/duff control points exist.

Now, the easiest way to get rid of these is the
"Control Points" dialog (F3), which can list control points
in distance order, making deletion quick and easy.

But this shows ALL the control points. In a partially
completed optimisation, the un-optimised images
(UN-selected in the preview) will have very large errors,
and this make removing the large(st) errors
for the selected images very difficult.

Feature request:

F3 should only show CPs for "image selected in preview window",
possibly also under the control of the option in the Optimise tab.

[tmodes (tmodes)]

Implemented in changeset 4deec1f508a6.
Please test if all works.