Added support for loading containers into specialized VisiData ``Sheet`` and ``IndexSheet`` subclasses; added ``to_visidata()`` exporter to all containers.
Added ``StyleConfig`` class for configuring display characteristics. Added default ``StyleConfigCSS`` for improved default HTML presentation.
Added ``Series.rank_ordinal``, ``Series.rank_dense``, ``Series.rank_mean``, ``Series.rank_min``, ``Series.rank_max``.
Added ``Frame.rank_ordinal``, ``Frame.rank_dense``, ``Frame.rank_mean``, ``Frame.rank_min``, ``Frame.rank_max``.
Fixed issue in ``Series.from_element()`` and ``Frame.from_element()`` that would broadcast some iterables instead of treat them as an element.
Extended ``Frame.unset_index()`` to support unsetting ``IndexHierarchy``.