I'll return to the merge conflicts after v2.3, given that this is a breaking change.

Given how many of these breaking changes arise from the analysis developed in specific issues, I've evolved my approach to the CHANGELOG by explicitly linking to those issues under each item. Feedback welcome on whether this is desirable or not!

At present, two existing such items are badly formatted, so at some point, we should fix those up, but I won't try to as part of this PR (though at some level, to me at least, it would 'make sense' to do so, to be consistent with the entry added here... ;-))

Just fixed a typo, and with it the chance to look over everything once again. I'd like to merge this, but at that point, we basically will have duplicate families Half*Adjoint and Inverse*, so downstream we should try to reconcile everything under a single sensible naming scheme...

I don't understand your comment about duplication? Yes, these are equivalent notions, but with rather different UX, so having them both is definitely a plus.

Thanks @JacquesCarette re:duplication. Will not fiddle any further.