- simplify the singleton pattern across the codebase
- reduce lines of code needed for crufty initialization
- reduce functions that need to mess with a global
- Singletons whose semantics changed:
- spack.store.store() -> spack.store
- spack.repo.path() -> spack.repo.path
- spack.config.config() -> spack.config.config
- spack.caches.fetch_cache() -> spack.caches.fetch_cache
- spack.caches.misc_cache() -> spack.caches.misc_cache