Naming consistency

[mor1]

I came across a possible naming inconsistency for `Class -- it seems to use `Style_Attr rather than the more consistent (to my mind) `Style_attr

[Drup]

The formating of poly variants in the phantom type is wildly inconsistent. I must say we don't pay much attention to it. We normalized the names of the elements last version, I'm not up to breaking compat again for something that is not critically user-facing (users see them, but should probably never type them themselves).

I'll keep it open for next time we are breaking compat. :p