Add Segmentation export using FreeSurfer label values #5
Description
Exporting a segmentation does not currently guarantee that labelmap values will match the expected values.
FreeSurfer segmentations are currently imported and assigned to segments using the FreeSurfer values, however the label values may not be the same on export (see related issue here).
Segmentation are currently only saved as NRRD, however we should add the option to export the Segmentations to other FreeSurfer formats (NIFTI, MGZ, etc.)
Related discussion https://discourse.slicer.org/t/export-segmentation-scene-mrml-and-segmentations-nrrd-into-nifti-format-for-dropbox-viewing/12517.