Explicitly doc inheritance (consistency check)

[rrfreimuth]

There are several places where the schema, generated docs, and class diagram do not explicitly describe the inheritance structure of classes. The following areas need to be proofed and updated as needed.

• SeqRef (left nav bar, should not be nested under Location)
• Location (should inherit from Identifiable Object)
• SeqLoc (should inherit from Location)
• SystemicVariation (should inherit from Variation)
• CopyNumber[Count|Change] (should inherit from SystemicVar)
• MolecularVariation (should inherit from Variation)
• All subtypes of MolecVar should inherit from MolecVar rather than Variation