Erin Sheldon

This PR has two parts. The first is to expose the ignore_zero_weight to the medsreaders, so we can create Observations with zero weights or uberseg with these zero weight pixels...

Filing only occurs when there are zero weight pixels, which is not the default for Observations. No examples in the /examples director showed using it. Anyone using admom with masked...

Yes you can, just construct the Observation with the default `ignore_zero_weight=True`

This results in an extra evaluation of the model over the pixels during each iteration, so is sub-optimal. I think we can probably eliminate some of the passes by pre-evaluating...

Note for some fitters, there can be multiple bands and can be convolved by the PSF

thanks for this

If the flag isn't being passed, this might be a python/pip issue

I tagged a new version and pushed to pypi

is this working now?

The docs say the underlying implementation will depend on data type, so we should make sure we get good coverage in the unit tests