GitLab

Utils used to depend on Distribution.Package, so Package couldn't
easily use Utils.  I removed this dependency by moving a couple of
functions into D.Package, then moved currentDir into Utils where it
belongs.

clean now removes preprocessed sources (and is  more likely to destroy your source code so be careful)

** now the sources are built in-place, not moved to dist before being built
** the bug was that for executables, the build was not putting the .o and .hi files in the right place.

End-to-end preprocessing solution, including some test cases.
One test case fails:
  right now, preprocessors just stick files into the current
  directory, then copies them into the destination.  this is no good
  since we now won't be able to tell them from real source files the
  next time around.  clean is broken here...