- 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
* Add several new R packages
* Add a few more R packages
* Update more versions
* Convert Package to RPackage
* Add a few more packages
* Add missing dependencies