- 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
Renames the existing bootstrap command to 'clone'. Repurposes
'spack bootstrap' to install packages that are useful to the
operation of Spack (for now this is just environment-modules).
For bash and ksh users running setup-env.sh, if a Spack-installed
instance of environment-modules is detected and environment modules
and dotkit are not externally available, Spack will define the
'module' command in the user's shell to use the environment-modules
built by Spack.
* Removing the nobuild, nolink, and alldeps dependency types in favor of being explicit.
* This will help with maintenance going forward, as adding more dependency types won't affect existing declared dependencies in weird ways.
* default deptype is still `('build', 'link')`
