Covers:

    * Path.match
    * Path.glob
    * Path.rglob
    * Path.relative_to
    * Path.is_symlink (with trivial implementation given the lack of
      symlink support currently)

along with an implementation of Path.__eq__ for testing/comparison
purposes.

Part of the implementation here makes use of CPython internals (from
the pathlib module) but it seems to handle fixing that requires some
refactoring upstream.

…d avoids platform-specific concerns.

… test on Windows. Added test for relative paths with subdirectories.

… Instead, assert that its string value resolves to the expected value.