[review] consider different trait names

[badair]

I'm not a big fan of names like "is_reference_member" for a trait that's actually "has ref-qualifier".
Likewise for something like "is_volatile_member"; my first reaction is "is it a pointer to member data of volatile-qualified type?". Maybe the namespace helps, I don't know.

from http://lists.boost.org/Archives/boost/2017/04/234173.php

[badair]

Good suggestion, but closing as won't fix.