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
* Remove +mpi variant from NCO
* Update NCO deps to AutotoolsPackage
* Update the other NetCDF packages to AutotoolsPackage
* ANTLR has a nolink deptype on java, don't worry about csharp
* Remove restrictions from NCO package, fix homepage
* Add version 4.6.3 of NCO
* Missed AutotoolsPackage for NetCDF-CXX4
* NetCDF tests fail when run in parallel
* Remove commented out dependency
* Add documentation dependency
