v0.20.0 Final

This is a major release from 0.19.2 and includes a number of API changes, deprecations, new features,
enhancements, and performance improvements along with a large number of bug fixes. We recommend that all users upgrade to this version.

Highlights include:

• new .agg() API for Series/DataFrame similar to the groupby-rolling-resample API's, see here
• Integration with the feather-format, including a new top-level pd.read_feather() and DataFrame.to_feather() method, see here
• The .ix indexer has been deprecated, see here
• Panel has been deprecated, see here
• Addition of an IntervalIndex and Interval scalar type, see here
• Improved user API when accessing levels in .groupby(), see here
• Improved support for UInt64 dtypes, see here
• A new orient for JSON serialization, orient='table', that uses the Table Schema spec, see here
• Experimental support for exporting DataFrame.style formats to Excel, see here
• Window Binary Corr/Cov operations now return a MultiIndexed DataFrame rather than a Panel, as Panel is now deprecated, see here
• Support for S3 handling now uses s3fs, see here
• Google BigQuery support now uses the pandas-gbq library, see here
• Switched the test framework to use pytest

See the Whatsnew file for more information.