- 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