KERML_ — Corrections to the resolution of KERML_-18

There are some errors in the OCL of certain operations add to Feature by the resolution of KERML_-18.

1. In isCartesianProduct, the first two conditions should not be part of the first operand of the following "implies" (otherwise, e.g., a feature with no type or featuring types would incorrectly be considered a Cartesian product).
2. In isOwnedCrossFeature, "owningType" should be "owningNamespace" (because owned cross features are required to be not owned via FeatureMemberships).
3. In ownedCrossFeature, ownedMembers owned via FeatureValues should also be excluded from the list of ownedMemberFeatures being computed.