Creates search scope objects from the provided preference store. Classes that
implement this interface should take settings manipulated in the search scope
preference pages and create scope objects that are required by search
engines. Search engine and scope factory are defined together in the same
extension point, hence the actual implementation of ISearchScope is up to the
Returns a new search scope object created from the data in the preference
store. Factories should be prepared to compute default values if they are
missing from the preference store. This can happen before users open
scope preference pages for the first time.
In cases where conflicting values can be found in the preference store
and parameters, preference store should win i.e. parameters should be
treated as default values only.
store - the preference store that holds the scope data
engineId - identifier of the engine instance that needs the scope object.
parameters - configuration parameters provided in the engine extension
point. They should be used as default values and preference
store values (if defined) should be given precedance.