Mask intersection overlay
Potentially useful feature: a new overlay type, a 'mask container' which allows the user to add mask images to it, and control how the intersection of the different masks are coloured.
Slightly related: fsl/fslpy#136
Potentially useful feature: a new overlay type, a 'mask container' which allows the user to add mask images to it, and control how the intersection of the different masks are coloured.
Slightly related: fsl/fslpy#136