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
* Ensure that every package has a license
Also fixes URLs with http://http:// doubled.
This is a continuation of #2656.
* Add license to every file in Spack
* Make sure Todd is the author of all packages
* Fix flake8 tests
* Don't license external Sphinx docs
* Don't display licenses in tutorial example packages
Also fixes typos and converts command-line examples
from tcsh to bash, which is more common
