complete the setup.py, fix #202 problem in posseg
backport 2to3 scripts and changelog
Merge pull request #203 from gumblex/master

修复 posseg；完善 setup.py
Fix divided by zero issue in case of words are not found in dict.
Merge pull request #205 from lynschinzer/master

Fix divided by zero issue in case of words are not found in dict.
Merge pull request #3 from fxsjy/master

[Sky Dragon] Merge