rset.possible_actions (which should definitly not be an ResultSet method, but
that's another story) has been designed to hold a cache to compute possible
actions for a only once, since this may be a fairly costly operation (notably
because of the 'has_editable_relations' predicates). But this has been broken by
introduction of a new 'view' parameter which is not given by every call.

To fix this, this cset adds the missing view argument where necessary and
reimplements the rset's method to assert it's always called with the same key.

Unfortunatly, those changes have to be ported to squareui and bootstrap cubes as
well.