Preparation for generic user views
Added a getSuffixValues method that is meant to allow for having a
non-public field as key_name.
Also added support for a key-name field being embeded in the form so
that if the key-fields change the old key_name is not lost.
Added support for providing a custom params dict
This has been a long outstanding feature request for tlarsen, luckily
it turned out to be very easy to implement with the dict.merge
utility method. To have custom _rights one should instead to the
required access checks before calling the view method.