On branch topic/fix-ZippyTempArchive
 Changes to be committed:
	modified:   OpenXLSX/external/zippy/zippy.hpp

+ Fixed a bug in the generation of the pathname for a temporary archive used
  during a save operation. The implementation was peeling out the path by
  searching for the last '/', but Windows-based systems generally use '\'.
  The net result is that the temporary file is created in the current
  directory instead of the directory of the existing archive. If the current
  directory happens to be a 'protected' directory (such as the standard
  Program Files directories) then the file creation will fail.
+ In the scenario above, the failure to create the temporary archive was
  not caught, resulting in the code proceeding and eventually failing, but
  without any error information attached. The fix, included here, is to
  check the return value of mz_zip_writer_init_file and throw if it fails.