BAZYNGO-1457: factored out Direction enum
BAZYNGO-1457: Factored out PropertyBasedComparator as a generalization
of AttributeComparator
BAZYNGO-1457: MultiAttributeComparator needs specification of direction
for each of the specified attributes. Also factored out
CompositeComparator concept.
BAZYNGO-1457: moved general comparators to ledge-web