Summary:
Updates for Release-4 of the ICESat-2 ATL14 and ATL15 products :tada:
**Itemized Changes:**
* `refactor`: simplify and generalize mapping between observables and functionals 42
* `feat`: minor updates for R004 43
* `docs`: bump `docutils` 43
* `docs`: use `importlib` rather than `pkg_resources` 43
**Full Changelog**: https://github.com/tsutterley/IS2view/compare/0.0.8...0.0.9