Move some styling out of the default style sheet
Move some styling out of the default style sheet

BREAKING: The default styling for lists and blockquotes was removed
from `prosemirror.css`. (They were moved to the
[`example-setup`](https://github.com/ProseMirror/prosemirror-example-setup)
module.)

ProseMirror/prosemirror-view,jspn500/prosemirror-view