Make DRC violations easier to locate

[Peter Clifton]

Feedback from John Bass:

While the DRC error report has the focus, it would be useful if a highlighted circle was drawn around the error location of the current highlighted error, on the main window of a size that would generally be reasonable ... maybe about a half inch of pixels. It would be nice if double clicking an error item, moved the cursor to that location, and moved the focus to the main window. Currently double clicking just flips the mouse pointer into a location on the main window, which is anything but useful.