Krasimir:
  added hs-source-dirs (ross added docs)

  Add other-files field to PackageDescription. This is a list files
  which belong to the package but aren't compiled. These files are
  copied and packaged from sdist command.

Ross:
  fixes to buildHugs and sdist after hs-source-dirs changes.
  
  Also simplified smartCopySources a bit.

  document sdist and new other-files field.