finished three class

Dictionary.java, WordList.java and Quiz.java all with Test
remove the controller's file
rollback
Merge branch 'master' of https://github.com/wangzhizhen/SE_Lab4
Fix the conflict
Merge remote-tracking branch 'origin/controller_branch'

Conflicts:
	src/controller/test/TestLetterPositionController.java
Fix the conflict
Add the Quiz class

为解决conflict删掉了该类，现在重新添加上去
finished all model class
Merge branch 'model_branch'
Merge branch 'master' of https://github.com/wangzhizhen/SE_Lab4
Merge remote-tracking branch 'origin/controller_branch'
Add getWordAt(int,int) method toDictionary class

Dicitionary漏加了一个方法，产生了bug