add person name and fact convenience functions; replace helper...OrEmpty functions with calls to maybe
add getCouple
add person convenience functions to getChildAndParents and getCouple
add getPersonRelationshipsToSpouses
add getPersonRelationshipsToParents
getPersonRelationshipsToParents returns an object with ids, not functions
rename getPersonRelationshipsTo... to getRelationshipsTo...
add getRelationshipsToChildren
add fact convenience functions in more places; add parent/spouse/child relationship convenience functison in getPersonWithRelationships