Replace PostgreSQL parser to libpg_query wrapper

[SoftStoneDevelop]

• #22.
• #23
• #24

This is start for create nuget(https://digitalhouseblog.wordpress.com/2019/08/22/how-to-make-a-nuget-package-for-c/).
This change improve nuget experience. Same parser like in postgre server. This means we can get return aliases in all cases(return, subquery, func).