Making it easier to add contours.

With improvements for BUG #14198 which made it easier to add annotations by
adding a new class for showing expandable tables, updating the panel for the
Contour filter to use the same widget.

Updated to tests to exercise some of the functionality of the update panel.

Change-Id: I69b667b3b428d66310363ea24ce9badfc0f2cc2f
Merge topic '14198_easy_add_contour_values' into next

53bdeb4 Making it easier to add contours.