We'd like to use a consistent checksum scheme everywhere so that we can:
a) incorporate archive checksums into our specs and have a
consistent hashing algorithm across all specs.
b) index mirrors with a consistent type of checksum, and not one that
is dependent on how spack packages are written.
- [x] convert existing md5, sha224, sha512, sha1 checksums to sha256
- 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 pango dependency
* add new package ghostscript-fonts & add to ImageMagick as dependency
also tell ImageMagick's configure where the font dir is!
* refactor to fix flake8
* add homepage to ghostscript-fonts
* use install_tree
* remove unneeded import
