Log Message:
Update from version 2.21 to 2.22.  Changes:

2.22 July 19 2008 - Minor Beta

    + Added JPEG support.

    + Added 29_process_jpg.t test for jpg dimension processing.

    + Turned off compatibility_mode() in Spreadsheet::WriteExcel::Big
      which was on by accident.

    + Added "Warning about Office Service Pack 3" section to the
      docs to explain Excel warnings with duplicate data.

    + Expanded "Dates and Time in Excel" section of the docs.

    + Added isa() to _process_images() to allow subclassing.
      Reported by David Worenklein.