draft proposition to enhance DRef pattern matching
minor: superfluous val
minor: revert DId.unapply

not needed, as it duplicates DRef.IsId.unapply
add overloads for DRef.apply

add overloads for DLong and Long, so that one can avoid DRef(DId(long))
Merge pull request #10 from pellucidanalytics/features/dref-enhanced

draft proposition to enhance DRef pattern matching