code: public void addWord(Word newWord, boolean makeCopy){
  		synchronized(words){
  			Word existingWord = words.get(newWord.getWord());
  			if (existingWord != null){
  				existingWord.setType(newWord.getTypes());
  				existingWord.setKeywordAttachment(newWord.getKeywordAttachment());
  			}else{
  				if (makeCopy){
  					newWord  = new Word(newWord);
  				}
  				words.put(newWord.getWord(), newWord);
  			}
  		}
  	}
docs: 加入一个新词条，如果这个词条在词典中已经存在，则合并。
  <p>
  Add a new word, if this word already exists in the dictionary then the new definition will
  be merged into existing one.
  
  @param newWord
  @param makeCopy	是否复制词条对象，而非引用
  <br>Whether or not to copy the Word object, rather than to refer it.