Static-frame

Added immutable, hashable containers ``SeriesHE`` and ``FrameHE``.

Implemented ``read_many`` for all ``Store`` subclasses; ``Bus`` now uses these interfaces for significantly faster reads of multi-``Frame`` selections.

Improved handling of connection object given to ``Frame.from_sql``.

Improved type-preservation and performance when assigning ``Frame`` into ``Frame``.

Improved handling for using ``Frame.iter_group`` on zero-sized ``Frame``.

``Series`` can now be used as arguments to ``dtypes`` in ``Frame`` constructors.

Added ``via_dt.strptime`` and ``via_dt.strpdate`` for parsing strings to Python ``date``, ``datetime`` objects, respectively.

Bus`` indices are no longer required to be string typed.

``StoreConfig`` adds ``label_encoder``, ``label_decoder`` parameters for translating hashables to strings and strings to hashables when writing to / from ``Store`` formats.

``Frame.from_sql`` now supports a ``columns_select`` parameter.

``StoreConfig`` now supports a ``columns_select`` parameter; ``columns_select`` parameters from ``StoreConfig`` are now used in ``StoreZipParquet``, ``StoreSQLite``.

Extended ``via_str.startswith()`` and ``via_str.endswith()`` functions to support passing an iterable of strings to match.

Improved ``IndexHierarchy.loc_to_iloc`` to support Boolean array selections.

Improvements to ``Quilt`` extraction routines.

Improved handling of invalid file paths given to constructors.

Improved implementations of ``Bus.items()``, ``Bus.values``, and ``Bus.equals()`` that deliver proper results when `max_persist` is active.

Implementation of ``Quilt``, a container that presents the contents of a ``Bus`` as either vertically or horizontally stacked ``Frame``.

Implemented ``__deepcopy__()`` on all containers.

Frame.iter_tuple_items()`` now exposes a ``constructor`` argument to control creation of axis containers.

Added ``Batch.apply_items``.

Added ``Frame.count``, ``Series.count``, ``Batch.count``.

Added ``Frame.sample``, ``Series.sample``, ``Index.sample``, ``IndexHierarchy.sample``, ``Batch.sample``.

Added ``Frame.via_T`` and ``IndexHierarchy.via_T`` accessors for opposite axis binary operator application of 1D operands.