def fix_utf8(s=nil)
      s=self if s.nil? #if we are included
      if String.method_defined?(:scrub)
        #Ruby 2.1
        #cf http://ruby-doc.org/core-2.1.0/String.html#method-i-scrub
        return s.scrub {|bytes| '<'+bytes.unpack('H*')[0]+'>' }
      else
        return DR::Encoding.to_utf8(s)
      end
    end
def fix_utf8(s=nil)
      s=self if s.nil? #if we are included
      if String.method_defined?(:scrub)
        #Ruby 2.1
        #cf http://ruby-doc.org/core-2.1.0/String.html#method-i-scrub
        return s.scrub {|bytes| '<'+bytes.unpack('H*')[0]+'>' }
      else
        return DR::Encoding.to_utf8(s)
      end
    end
if a mostly utf8 has some mixed in latin1 characters, replace the
invalid characters