0.8.8 November 17 2019

• Added option to allow a user defined, or overridden, image description used
  with worksheet_insert_image(). By default it uses the filename as the
  description.
  Issue #238.

• Added Windows portable version of fopen to handle utf8 filenames when
  working with images.
  Issue #238.

• Added an option to allow chart fonts to be rotation to 270 deg to give a
  stacked orientation. Also added support for East Asian vertical chart fonts.

• Refactored struct types used in pubic APIs to remove or document hidden
  fields. Note: This change introduces backward incompatible API
  changes. However, it should minimize any future changes of this nature.
  See issue #252.