WIP using the new XTK version.
Reset bounding box.
Use the latest compiled XTK edge.

Also, change default color to white and adjust the upperWindow for volumes to have better default contrast.
Work in progress to update SliceDrop to the new XTK version.
No need for reseting the boundingbox anymore.
Update to match newest XTK version.
Add dropbox.min.map to avoid an error and put the computing callbacks in place.
Match the addcomputingprogress of XTK.
Add default lowerThreshold when volumerendering is activated.
Add the computing progress callback.
Add callbacks for the slice navigation.
Almost ready for release.
Add anatomical labels.
Merge branch 'fix_orient'