Simplify contrast query
add: filtering volume (separate from small-volume correction)
If no range found for current attribute throw an incorrect range error
DisplayMaskMap, minDistanceBetweenPeaks and maxNumberOfPeaksPerCluster
DisplayMask is only a mask

- Remove attributes: maxNumberOfPeaksPerCluster and
minDistanceBetweenPeaks (to be stored in a separate entity)
Definition for DisplayMaskMap
DisplayMaskMap definition (update by @nicholst)