Checkpoint commit: much-improved spec class.

bin/spack

lib/spack/spack/cmd/clean.py

lib/spack/spack/cmd/compilers.py

lib/spack/spack/cmd/create.py

lib/spack/spack/cmd/list.py

lib/spack/spack/cmd/spec.py

lib/spack/spack/cmd/versions.py

lib/spack/spack/colify.py

lib/spack/spack/color.py

lib/spack/spack/compilers/__init__.py

lib/spack/spack/compilers/gcc.py

lib/spack/spack/compilers/intel.py

lib/spack/spack/dependency.py

lib/spack/spack/directory_layout.py

lib/spack/spack/globals.py

lib/spack/spack/multi_function.py

lib/spack/spack/none_compare.py

lib/spack/spack/package.py

lib/spack/spack/packages/__init__.py

lib/spack/spack/relations.py