0.04 - 28-May-2007
    * Accepting IO::Handle as 'file' argument to allow for instance
      building spreadsheets in memory (using IO::Scalar).

0.03 - 25-May-2007
    * Formats are cached to improve performance in Excel
    * 'content' in extended cell info blocks can be an array to simplify
      headers creation and such.

0.02 - 7-May-2007
    * 'width' added to set column widths

0.01 - 5-May-2007
    * Original release