[Rodrigo Coelho]

Proposal: a different approach on scopes.

• DRY: Scopes must be defined only in the "scopes" method or in their own methods (for parameterized ones). In the method "defaultScope", there should be only a reference to a previously declared scope.
  
  
• Resetting: Ability to reset only selected scopes. This improves maintanability. The motivation for this is that you can't specify a scope that disables a default scope*. Having the ability to disable only a selected scope improves maintanability because it is not needed to review/change every query where scopes are reset.

* You can't specify the scopes "active" and "inactive" in the same query, since the resulting query will have something like this: "WHERE active = 1 AND active = 0". Another proposal would be to have something like "binary" or "overridable/grouped" scopes. The developer could specify an id to the scopes and when another scope of the same id is applied, the former scope is overriden by the new scope.