v0.18.1 Final

This is a minor release from 0.18.0 and includes a large number of bug fixes
along with several new features, enhancements, and performance improvements.
We recommend that all users upgrade to this version.

Highlights include:

• .groupby(...) has been enhanced to provide convenient syntax when working with .rolling(..), .expanding(..) and .resample(..) per group, see here
• pd.to_datetime() has gained the ability to assemble dates from a DataFrame, see here
• Method chaining improvements, see here
• Custom business hour offset, see here
• Many bug fixes in the handling of sparse, see here
• Expanded the Tutorials section with a feature on modern pandas, courtesy of @TomAugsburger (:issue:13045).

You an install the latest version of pandas via conda:

conda install pandas -c conda-forge