code: public static void addPlural(String match, String rule, boolean insensitive){
          plurals.add(0, new Replacer(match, rule, insensitive));
      }
docs: <p>Add a match pattern and replacement rule for converting addPlural
  forms to addSingular forms.</p>
  
  @param match Match pattern regular expression
  @param rule Replacement rule
  @param insensitive Flag indicating this match should be case insensitive