fix Vec3f error
Complete triangle
A LARGE COMMIT: Rendering structure
changes:
1. Poor3D.h includes everything for you
2. Rendering utilities
3. some Adjestment in CoreEngine for checking result. For example, I
turned OpenGL version to 2.1, so that I don't have to write shader.
4. Add operator overloading function in Vec3f.h
5. New test code