- 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 packages for clustalw and clustalo (and argtable)
Add packages for the classic multiple alignment package, `clustalw`
and its younger sibling, `clustalo`.
`clustalo` needed the `argtable` package (command line arg parsing).
Lightly tested on CentOS 7.
* Remove FIXME (sigh...)
