make use of FromFinalId type class in DDatabase

remove need for overloading of .entity .entid .ident and .touch
seal FromFinalId trait
introduce FromPointT type class

eliminate overloading for point in time methods
remove implicit view to Long from FromPointT

seems unnecessary, unlike the cases for ToDId and FromFinalId
refactor the type classes for ids and point t

choose better names
make the methods package protected
add scaladoc as they deserve some explanation
Merge pull request #70 from pellucidanalytics/topic/overloads

Eliminate method overloading in DDatabase