Update README.md
Merge remote-tracking branch 'origin/xiangqun'
Fix PKB build bug
Merge branch 'master' of https://github.com/hugle/SPA_NAVI into xiangqun
really fixed the ~List() bug
Merge branch 'master' into xiangqun
Merge remote-tracking branch 'origin/xiangqun'
Merge branch 'master' into xiangqun
Add {} behind ~X; now it becomes ~X{}
Merge branch 'master' into xiangqun
possible fixed?
Merge branch 'master' into xiangqun
QueryPreprocessor renamed to QueryValidator