Hygiene: use the same base HTML in normal editor and VE

All the headers are the same, edit summary and captcha panels are the
same too. Incidentally, this fixes the preview header in VE.

Also, move EditorOverlayBase files to editorNew directories (it's not
used in stable and uses OverlayNew).

Change-Id: I1638fc967747976ccc69b18aa24ab7c38642b10a
Merge "Hygiene: use the same base HTML in normal editor and VE"