UI : Focus on selected control point.

When we select an image under a control point in the tree, it should show the image focused on this control point. It often appear out of the view and we must always unzoom / rezoom to search the control point.

Additionally, ALT + click on the point to directly behave like if I was dragging the control point will be even faster. So there’s no need to go click on the tiny control point in the image, risking of setting an unwanted control point if we miss it.