stereotypes: add model multiple concepts scenario
diagrams: add all designed concepts to SML model
agile: backlog Check concept properties for identity

- this is not a requirement to implement the SML changes needed for
  this iteration.
cpp: add concept properties in order of inheritance
cpp: ensure extractor takes concepts into account

Previously we didn't have any scenarios where a concept had a property
of a non-primitive type. We missed a bug in header file inclusion. Add
scenario for this and fix the bug.
sml: implement modules in terms of concepts
sml: implement concepts in terms of concepts
sml: create a primitive type again but now using concepts