1) added a utility method addHeadTailSpace() to StringUtility class, and test cases of it. 2) finished a helper of tagAllSentence() in Leaner class.
1) added some new code to annotateSentence(). 2) renamed addHeadTailSpace() to replaceAllBackBackreference(), and changed its code. 3) added a utility setSub() and test cases. 4) renamed os -> organs in KnownTagCollection class.