Pickle subclass metadata
Fixes #10553

might be able to remove setstate from Series as well (it will use the inherited then)
 > might be able to remove setstate from Series as well (it will use the inherited then)

Apparently so. Done.
 awesome!

can u add a note in whatsnew (u can put under API changes)

and squash

ping when green
 @jreback green and squashed like mashed peas.
 thank you sir!
 SciPy was really amazing btw

really cool that so many from industry, academia, and technology get together!
