Segmentations + PET overlay

[mlavik1]

#249

Add support for PET overlays and segmentation labels.

Features:

• Import PET dataset (and use separate transfer function for this)
• Import segmentation
• Combine imported segmentations automatically
• Set colour for each segmentation labels
• Segmentation render modes: Overlay and isolated

TODO:

• Allow creating a transfer function for each segmentation label (stack these on top of each other in final combined TF - note: Will need point filtering mode for that)

Datasets for testing:

• Segmentations: https://zenodo.org/records/8367088
• PET/CT: https://www.aliza-dicom-viewer.com/download/datasets (see "TCIA, Siemens, PET study")

[mlavik1]

[mlavik1]

Isolated isosurface rendering