Minor release 0.16.0

[hakonanes]

I suggest we make a minor 0.16.0 release right away, as we have a couple of bug fixes and deprecations in and some good updates to (mis)orientation reduction and the mean calculation (more correct, supports weights).

Looking at the open PRs, I think we should only get these in before releasing (as the others may take more time to review):

• Add .oh5 reader for EDAX/OIM EBSD files #657
• Add missing point groups #647

@argerlt and others, any thoughts?

[argerlt]

Sounds good to me, the unreleased section has gotten pretty beefy in the last two weeks.