Merge branch 'develop' into features/cache-archives

.flake8

bin/spack

lib/spack/docs/basic_usage.rst

lib/spack/docs/configuration.rst

lib/spack/docs/features.rst

lib/spack/docs/packaging_guide.rst

lib/spack/env/cc

lib/spack/llnl/util/tty/__init__.py

lib/spack/llnl/util/tty/colify.py

lib/spack/spack/__init__.py

lib/spack/spack/abi.py

lib/spack/spack/architecture.py

lib/spack/spack/build_environment.py

lib/spack/spack/cmd/arch.py

lib/spack/spack/cmd/compiler.py

lib/spack/spack/cmd/find.py

lib/spack/spack/cmd/uninstall.py

lib/spack/spack/cmd/view.py

lib/spack/spack/compiler.py

lib/spack/spack/compilers/__init__.py