Implementing the new IDIF features requested by Jean Logan. Select top voxels {%,count,mm3}
at each individual timepoint to keep as a part of the IDIF mask.

Implemented Liver DCDI  Blood Vessel Segmentation 3D:  this is an alternative algorithm that uses a single pre-contrast timepoint  assuming the vessels are darker than the liver tissue.  Existing "Dark Ridge detection"  algorithm is used.  Existing Ridge dialog box is called.
Two ROIs are returned one for organ and the other for blood vessel.  There is no differentiation between Arterial and Venous vessels as in Segment4D variant.

Implemented and added an UI item  "MainMenu>Segment>Segment dark ridges"  which complements the existing "Segment bright ridges" functionality.

Implementing a 3-D base variant of the Blood Vessel Segmentation map.  This is in addition to the existing 4-D segmenter so the best option could be chosen.