Allow editing of testset name.

[theogf]

The automatic testset naming is pretty nice but can also be cumbersome when passing heavily parametrized functions.
In my case (no MWE here sorry) it breaks the whole display.
Would you be open to a PR adding a testset_name kwarg to override the automatic one?

[oxinabox]

I think that would make sense.
So if you pass nothing it falls back to the default?

[theogf]

Yes exactly, so this would just be an opt-in thing.