Due to regexp, its possible that its output has no length. Check to avoid errors.

MatLab's strcmp barfs on zero length strings which look like arrays (?).  Thus
avoid calling it with that to avoid errors.


git-svn-id: https://groke.mcmaster.ca/svn/grad/colin/trunk/TableTool@8512 57e6efec-57d4-0310-aeb1-a6c144bb1a8b