Func Fits: Weights and bug fix

[profxj]

Enables use of weights
Fixes a bug in final fit

[weaverba137]

In the future, can you please insist that all PRs on desiutil include an update to changes.rst prior to merging? That or only let me do all PR merges.

[sbailey]

Thanks for the reminder. "git log --oneline" can help retroactively figure out what should have been in changes.rst, but it is less human-readable than a curated changes.rst . Directly editing docs/changes.rst via the github can be a lightweight way of adding a comment if one initially forgot.

[weaverba137]

In this case git log --oneline gives "weights and mask". Not very enlightening.