xgrg/nisnap: v0.4

• Mostly updates in relation to some FREESURFER specific structures (amygdala, hypothalamus, thalamus, brainstem, etc..)
• utils.__make_legend__
• margin can be passed as an argument
• some code cleaning

• @jhuguetn made their first contribution in https://github.com/xgrg/nisnap/pull/1

nisnap uses some trick to identify ROI/label volumes against raw background images, based on the ratio number of zeros / number of voxels in the image. That trick prove to be stable with respect to the previous criterion (taking the number of distinct intensities in the image), but it might still fail sometimes.

Full Changelog: https://github.com/xgrg/nisnap/compare/v0.3.7...v0.4