Some nice-to-have features for verifying that conversions work #35
Description
It's hard to know that the to-h5 conversion worked. We should add some convenient outputs to verify that the spatial mapping and masking worked as expected.
- Write out a "mean" image in the original format
- Write an elementID image in the original format
- Write a N non nan image in the original format
- double check that mapping the element IDs matches