Merge pull request #127 in G/fastr from ~MICK.JORDAN_ORACLE.COM/fastr:feature/message to master

* commit '02a27b05':
  use Class.isAssignableFrom instead of switch on class name
  copyright fix
  Add RNull
  ForeignAccess: add RPairlist, fix try warning
  ForeignAccess: delete sample concrete vector classes
  ForeignAccess: reinstate RAbstractVectorAccessFactory due to lack of subclass support in MessageResolution
  Fix case fall through
  MessageResolution: cannot use abstract classes
  Add missing files
  Refactor RForeignAccessFactory using MessageResolution/Resolve annotations; All RTypedValue's are TruffleObject's