Got initial addition of min/max as labels working

Constraints in horizontal orientation need to be added to keep min/max
labels from overlapping others.

Change-Id: I31e0a26655cd7744421c2ba798fa9ab336a4bdd5
In horizontal orientation, change justification of min/max labels

Use right justification on the left side, right justification on the
left. This moves the large min/max labels outside the scalar bar
and prevents them from overlapping the other "nice" labels.

Change-Id: I18297dda57d9ac12228a887f193b5132ebc1f32f
Turn off visibility of labels that overlap min/max labels

Change-Id: Ife1dfc5ea581c73ab1ccde93ed9379f73b71c5d8
Draw major ticks only for labels that are visible

Change-Id: I5606fd947206f6454f758a72caf928db0385777a
Made min/max labels optional and added formatting string for them

Change-Id: Ie4c02f641a43829a1f0bec8d55dbe4bf3589b740
Added test for min/max labels in color legend

Change-Id: I7096749bd39cf1dcd8a8113871d5fe378ee13155
Merge topic '14696_min_max_labels' into next

3d0ff4f5 Added test for min/max labels in color legend
6be7e1b3 Made min/max labels optional and added formatting string for them
b64cfaa2 Draw major ticks only for labels that are visible
18d17444 Turn off visibility of labels that overlap min/max labels
e1c5fd3d In horizontal orientation, change justification of min/max labels
fd618e2e Got initial addition of min/max as labels working