Log Message:
Update from version 2.18 to 2.21.  Changes:

2.21 March 9 2008 - Major

    ! Fixed bug where UTF-8 strings in formulas weren't handled.
      Thanks Sergey Zhuravlev.
      http://rt.cpan.org/Public/Bug/Display.html?id=30368

    ! Fixed collapse outlines compatibility with Gnumeric
      and OpenOffice.org.
      Reported by Barrie Slaymaker.
      http://rt.cpan.org/Public/Bug/Display.html?id=33662

    + Added outline_collapsed.pl example.

    + Added document section about rewriting Excel files.

    + Minor security fix to Format to avoid eval and
      additional fix for RT 24218.
      Thanks to Bram.

    + Added increased compatibility with third party
      Excel reading applications such as POI.

    + Added optional compatibility_mode() to fix problems
      that can occur with Office SP3.

    + Fixed compatibility problem with Google Docs.

    + Added set_start_page() method for setting the start page
      number when printing.

2.20 October 6 2007 - Major

    + Added autofilter() and filter_column() method and
      autofilter.pl example.

    + Added embed_chart() method to allow extracted chart
      templates to be embedded in a worksheet.
      Added demo4.pl and demo5.pl examples.

    + Added the insert_image() method and proper Excel 97
      style image handling for PNG and BMP.
      Images now work with Gnumeric and OpenOffice.
      insert_bitmap() is now deprecated.

    ! Made pane split optional when calling freeze_panes().
      Also renamed thaw_panes() as split_panes(). The old
      method name is still available, but deprecated.

    ! Renamed write_unicode() and write_unicode_le() methods
      to the more explicit write_utf16be_string() and
      write_utf16le_string(). The old method names are
      still available, but deprecated.

2.19 June 14 2007 - Major

    + Beta testing only. Not released to CPAN.