Boilerplate added

This commit represents just about all of the essential scaffolding needed
to get working with OpenGL via GLFW and GLEW. We:
- initialize a GL context
- register a range of callbacks for this context
- load GL extension compatibility mechanisms
- create our render loop with necessary buffer swapping and event polling
- perform some clean up of previously allocated resources
Merge branch 'master' of https://github.com/b-willard/opengl-boilerplate