Swifter

Add an option `allow_dask_on_strings` to `DataFrameAccessor`. This is a non-recommended option if you are doing string processing. It is intended for using the string as a lookup for the rest of the dataframe processing. This override is also included in `SeriesAccessor`, but there I am not aware of a use-case that it makes sense to use this.

Swifter now defaults to axis=0, with a NotImplementedError for when trying to use dask on large datasets, because dask hasn't implemented axis=0 applies yet.

Added documentation and code styling thanks to msampathkumar. Also included override options for dask_threshold and npartitions parameters.

Added support for rolling objects in syntax that reflects pandas. `df.swifter.rolling(..).apply(...)`

Fixed a bug that would call a vectorized function when in fact the vectorization was wrong to apply. We have to ensure that output data shape is aligned regardless of apply type.

Added TQDM support (to disable do `df.swifter.progress_bar(False).apply(...)`, removed groupby_apply (because it's too slow), and tweaked some under-the-hood _dask_apply functionality. Specific functionality changes for pd.Series.swifter.apply include falling back to dask apply if dask map_partitions fails. Specific functionality changes for pd.DataFrame.swifter.apply include falling back to pandas apply if dask apply fails.