Finished a case in updatePOS method. Fixed a bug in method getPluralRuleHelper.
updatePOS method finished. No test cases added yet. Added equals and hasCode methods to class WordPOSKey.
method mergeRole has been finished. All test cases of it have been added. The first case of method changePOS has been finished.
remove unused database parameter code and relate code. Clear up the code a little bit, especially at the beginning part.
put all finished modules in learn method.
a few minor changes.
Method changePOS has been finished.
Merge pull request #10 from dongyemeng/master

Merge latest.