Discuss modifications to grains.out files

[psavery]

We are considering adding metadata to the grains.out file (such as whether or not the grain parameters were energy corrected).

However, we may want to add a lot of metadata to the grains.out file, such as the instrument config. In this case, we might want to have a whole new format, such as an HDF5 file (maybe using the NEXUS format), that contains everything about the grains.out file and the settings used to produce it. Or, we may explore having a separate metadata file. We should continue to discuss these things.

[ZackAttack614]

Linked to #580 .