support pointer locking.

makes longer journeys more enjoyable.

js/pixl/public/trixl.html

			}
		}
	</script>
	<script>
		var polyfill = {};
		polyfill.pointerLockElement = function() {
			return document.pointerLockElement ||
				document.webkitPointerLockElement ||
				document.mozPointerLockElement;
		}
		Element.prototype.requestPointerLock =
			Element.prototype.mozRequestPointerLock ||
			Element.prototype.webkitRequestPointerLock ||
			Element.prototype.requestPointerLock;
		polyfill.mouseEvent = function(ev) {
			ev.movementX = ev.movementX || ev.mozMovementX;
			ev.movementY = ev.movementY || ev.mozMovementY;
			return ev;
		}
	</script>
	<script src="gl.js"></script>
	<script src="geometry.js"></script>
	<script src="matrix.js"></script>
				mouse.last = {x: ev.clientX, y: ev.clientY};
			}
			var diff = { x: mouse.last.x - ev.clientX, y: mouse.last.y - ev.clientY };
			ev = polyfill.mouseEvent(ev);
			var diff = {
				x: -ev.movementX || mouse.last.x - ev.clientX,
				y: -ev.movementY || mouse.last.y - ev.clientY
			};
			trixl.camera.rotate(diff.x * trixl.speed.turn, diff.y * trixl.speed.turn);
			mouse.last = {x: ev.clientX, y: ev.clientY};
		});
		trixl.stage.addEventListener("mousedown", function(ev) {
			if (polyfill.pointerLockElement() === null) {
				trixl.stage.requestPointerLock();
			}
		});
		window.onresize = function() {
			trixl.window.w = window.innerWidth;
			trixl.window.h = window.innerHeight;