Don't try to create two EXTRA_DIST entries, that won't work
Remove files from tarball again that don't actually belong there

These are things apparently in the git repository for convenience, but
that aren't actually part of the code base -- so don't ship them in the
tarball
Make this 8 spaces rather than a tab, so that things line up nicely
Better cleaning of python files

- Add a dot, to clarify that this must be an extension
- Add the same to the tools/rdm Makefile (the other ones in the python
  directory already have it)