• Added Python 3.7 support
• Added support for pandas <= 0.23.1
• Added dt and str accessors to Series
• Added support for passing an integer (sheet index) as sheet_name to StyleFrame.read_excel
• StyleFrame.read_excel sheetname argument changed to sheet_name. Using sheetname is still allowed but will
  show deprecation warning.
• Added Styler.combine method.
• Added utils.number_formats.decimal_with_num_of_digits method.
• Added overwrite_default_style argument to StyleFrame methods apply_style_by_indexes and apply_column_style