Fix issues with auto- and manual-controls; fix readout value formatting [1389]

The Auto-scale and Manual scale widgets were always enabled.  This created an ambiguity.  In addition, the numeric readout of the scale values did not always follow the widget choice.  In addition, for Transect plots, the formatting of the values was horrible.  I did have to add a method in TransectControl to override a (new) method in CrossSectionControl to get the actual range of the transect line values available in CSC so the labeling would be correct.