message: Added some useful OpenGL diagnostics.
  We might not want to print them out all the time but we might want
  to stash them in the GraphicsContext and make them retrievable through
  a function.
diff: @@ -114,10 +114,32 @@ impl GraphicsContext {
  screen_width: u32,
  screen_height: u32)
  -> GameResult<GraphicsContext> {
  +
  + let gl = video.gl_attr();
  + println!("Default to GL {}.{}",
  + gl.context_major_version(),
  + gl.context_minor_version());
  +
  + gl.set_context_version(4, 3);
  + gl.set_context_profile(sdl2::video::GLProfile::Core);
  +
  + println!("Asking for GL {}.{} {:?}",
  + gl.context_major_version(),
  + gl.context_minor_version(),
  + gl.context_profile());
  +
  +
  let window_builder = video.window(window_title, screen_width, screen_height);
  let (mut window, mut gl_context, mut device, mut factory, color_view, depth_view) =
  gfx_window_sdl::init(window_builder).unwrap();
  +
  + let gl = video.gl_attr();
  + println!("Actually got GL {}.{}, profile {:?}",
  + gl.context_major_version(),
  + gl.context_minor_version(),
  + gl.context_profile());
  +
  let encoder = factory.create_command_buffer().into();
  let pso = factory.create_pipeline_simple(include_bytes!("shader/triangle_150.glslv"),
  