Merge pull request #14 from crumblingstatue/master

Fix compile error
Merge pull request #15 from crumblingstatue/master

Fuck ifndef, use pragma once
Merge pull request #16 from crumblingstatue/master

gomu::exec() Actually call quit()
Merge pull request #17 from crumblingstatue/master

Add gomu::quit(), which requests GomuEngine to quit