AccountConcept, BlockConcept, MessageConcept, NetworkConcept and StateConcept should have a common definition format
Definitions should use 'classes' instead of 'concepts' for clarity and accuracy (properties are also concepts but are not classes, and are not subclasses of the 'concept' classes)
Changed previously agreed upon definition of accountConcept and EthOnConcept for consistency
Standardize general concept definitions