Saving an NDCube

[hayesla]

Description

After a recent discussion, I had with @grahamkerr, there may be a use case for write functionality of an NDCube (e.g. to a fits file). From what I can tell there doesn't seem to be one at the moment (however maybe I'm missing it?).

The easiest thing I guess would be to save the wcs and meta to a fits header and then save to a fits file with the nd-data array. However this may also not be a good idea, and maybe hard to generalize for sequence/collections.

But something to think about - any thoughts @DanRyanIrish @Cadair

[DanRyanIrish]

This is certainly something that has come up and documented in issue #111. Let's redirect this conversation to that issue.