to do
/////

* Use rpartition for getting the package of a module.

    + Make sure that an empty string is acceptable for __package__.

* Create meta_path importer for sys.path.

    + Create hook.
    + Rewrite Import to use the hook.

* Implement PEP 302 protocol for loaders (should just be a matter of testing).

    + Built-in.
    + Frozen.
    + Extension.
    + Source/bytecode.

* Public API to expose (w/ docs!)

  + abc

      - Finder

        * find_module

      - Loader

        * load_module

      - ResourceLoader(Loader)

        * get_data

      - InspectLoader(Loader)

        * is_package
        * get_code
        * get_source

      - (?) SourceLoader(ResourceLoader)

        * source_path
        * bytecode_path
        * write_bytecode

  + util

      - get_module decorator (new name)
      - check_name decorator (new name)
      - resolve_name

  + machinery

      - (?) Chained path hook/finder
      - BuiltinImporter
      - FrozenImporter
      - (?) FileFinder
      - Extensions importers

          * ExtensionFinder
          * (?) Loader

      - Source/bytecode importers

          * SourceFinder
          * (?) Loader

* Write benchmark suite.

* OPTIMIZE!

  + Fast path common cases.

    - Absolute name from sys.path.
    - Relative name from sys.path.

* Bootstrap importlib as implementation of builtins.__import__