CHANGE: PartialEq for Distributions

[Will-Low]

Summary

I'd like to be able to compare distributions to one another, defined as comparing their fields for equality. I'm trying to understand if there is a reason why this isn't currently implemented.

Details

I think this could be added to distributions by just added the PartialEq derive macro.

Motivation

When conducting unit tests, I'd like to be able to compare a created distributions to an expected distribution to they can be considered equal. In #560, it appears this idea was discussed, but people didn't think there was a need. I personally think the unit test case is compelling.

Alternatives

I'm not aware of another way of handling the equality check, since the distribution fields are private.

[dhardy]

I can see some utility of PartialEq for distributions in unittests and don't see a reason not to have it. @vks do you agree?

[vks]

Sure, why not. We also implemented it for the RNGs.