update to utilize a proper off-axis projection including a demo scene to prototype all systems

src/main.rs

@@ -41,8 +41,8 @@ fn main() {
 
         .add_startup_system(offaxis_camera_setup)
         .add_plugin(CameraProjectionPlugin::<OffAxisProjection>::default())
-        .add_system(update_offaxis)
         .add_system(simulate_viewer)
+        .add_system(apply_viewer_to_projections)
         .run();
 }