turn temp and final id overloads into type class
remove unneeded AddEntity overloads
minor: rename addRaw to addEDN
minor: use ToDId for DId.apply
Merge pull request #66 from pellucidanalytics/topic/id-overloads

Make overloading of temp and final ids uniform
Merge branch 'maintenance' into topic/implicit-conv

Pull in upstream changes.
minor: seal the ToDRef and DId traits
minor: fix use of DRef (should use DKeyword)
support singleton writes to set-valued ref attributes

the value for a cardinality-many, reference attribute can either be anything convertible to DRef or a traversable collection of anything convertible to DRef