Improve auto-completion in editor

[taozuhong]

1. Improve IntelliSense data: SQL -> AST -> ???
   reference project:
   https://github.com/taozhi8833998/node-sql-parser
   https://github.com/lulumengyi/Hive_SQL_AST
   https://github.com/cheng-zhao/libast

2. Show more precise auto-completion data