Let CF box on Display page link to subsection of editing page

Additionally to aca8b3b9cecb55072d5efc0efedbca04e7f2222a for users with lot of
CFs in groups AND CFs not in groups, this lets you jump to the right place
if you choose to edit a CF which isn't in groups.
Merge branch '4.2/cf-anchor' into 4.2-trunk