Some cleanups in the DICOM importer, and fix importing some sequences

Some DICOM sequences had each slice with an independent Series Instance
UID, thus confusing the importer which would import each slice as a
separate volume. Now we rely on Series Description, hopefully more
reliable. I also removed the Series Number from the volume signature.
Correct some stuff in ROI loading, still buggy
ROI manager is hard coded for unsigned char images, convert input
Remove useless labels from ROI list
Compute local and global orientations when reading fibers if they weren't there
Color modes list updated automatically
Correct errors in fiber stats computation
time is now managed by the navigator, interactor have the responsbility to update the sequence being view.
TimeLine is now managed only by the navigator. it is updated accordingly to the data in the view rely on metaData.
intercator for 4d mesh now inherit from 3d mesh.
Remove old declaration in vtkDataMesh4DInteractor and force update of the view when one call medVtkView::update (by calli,g Modified on view2/3d.)
One QTimeLine to rule them all.
Fix timeLine alwas visible issue.
updates the total number of frame label when layer added/removed
modification in medTimeLineParameter::nextframe method
cleaning
Relplace 'frm' by 'frames' in the medTimeLine widget.
Add a test to not set twice the same time sequence + typo corrections
Remove useless line that was trying to add a NULL widget to a layout
use value instead of const ref in medVtkViewItkDataImage4DInteractor::setCurrentTime