Optimize edit by calculating the set of restricted accessors only once
at class generation instead of calculating it each call.
Optimize edit by using the same technique to decide if getattr or
guarded_getattr has to be used to get the property.

TempBase had to be special-cased to keep compatibility with some
existing usages of calling TempBase.edit(modification_date=...) where
somewhere in CMF classes a protected setModificationDate exists. Instead
of rewriting existing cases to use something lighter (why do we need
TempBase anyway ?), we do minimal compatibility fix for TempBase only.