Visual comparison of a segmentation to a reference

Visual comparison of a segmentation to a reference, binary segmentation comparison showing the agree/over/under segmentation regions, `visual_comparison_of_segmentation`, in [this notebook](https://github.com/InsightSoftwareConsortium/SimpleITK-Notebooks/blob/master/Python/05_Results_Visualization.ipynb). Compatible with Slicer's `.seg.nrrd` metadata schema for quick overlay in Slicer.