When moving the Screen, move the Engine also so that things are drawn correctly.
When drawing hitboxes for the debug console, adjust their position by the position of the screen.
Adjust mouseFlashX/mouseFlashY when screen is moved.
Adding screen shake function.
Adding shakeStop function to stop a currently running shake.
Minor correction to shake magnitude. Include right/bottom end.
Refactoring shake to only move the screen once each frame.
Don't subtract screen position from draw dimensions.
Merge pull request #270 from bendmorris/letterbox

Allow moving the screen for letterboxing or screen shake.