- remove the old LGPL license headers from all files in Spack
- add SPDX headers to all files
- core and most packages are (Apache-2.0 OR MIT)
- a very small number of remaining packages are LGPL-2.1-only
* Added a package for the MDAnalysis toolkit.
* Adding a package for the Python virtualenvwrapper pacakge. Included
dependent virtualenv-clone and stevedore packages. Updated py-pbr with
a new version to support this.
* Added extra necessary dependencies and fixed the file download paths.