Using SPARQL with many filters seems to be a good way to go.
Pulled the Diagram related metrics into a separate plugin and factored out Karl's singletons into ontometrics-core
  - created a new toplevel maven project that builds all modules.
Fixed plugins-axiomatic metrics that needed to point at the previously moved Singletons now in ontometrics-core
  - Tarted up the description and metric abbreviation in AtomSubsetAtom to reflect its new calling in life.