code: public static RuleManager getInstance(Language language, Boolean load_temponym_resources) {
  		if(!instances.containsKey(language.getName())) {
  			RuleManager nm = new RuleManager(language.getResourceFolder(), load_temponym_resources);
  			instances.put(language.getName(), nm);
  		}
  		
  		return instances.get(language.getName());
  	}
docs: singleton producer.
  
  @return singleton instance of RuleManager