ENH: adjust the scale slider widgets to volume slice spacing
requested to merge github/fork/naucoin/3547-match-markups-scale-to-volume-spacing-Squashed into master
On entry to the Markups module, check for a background volume in the red slice viewer, get the slice spacing and adjust the scale slider maximum values by a scale factor times the maximum slice spacing. Round the max scale to the nearest 10 when resetting it from volume spacing. Also ensure that if the module is entered with scale values on the display node that are larger than the slider maximums that the sliders are adjusted. Also works for the default settings being larger than slider maximums. Set the scale factor to 10 to allow for large markups on widely spaced volumes.
Issue #3547