- Add version 2.1.0
- Now that #9264 has been merged, gplates seems to build fine with newer
versions of gcc (tested with gcc@8)
- When using the ninja generator, gplates can be built in parallel
- 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