look around with mouse.

not finished, doesn't really allow you to turn around, should probably
use two degrees of rotation. needs some research before i can implement
it.

js/pixl/public/trixl.html

			trixl.input.keys.delete(ev.keyCode);
		});
		trixl.input.mouse = {last: null};
		trixl.stage.addEventListener("mousemove",  function(ev) {
			var mouse = trixl.input.mouse;
			if (mouse.last === null) {
				mouse.last = {x: ev.clientX, y: ev.clientY};
			}
			var diff = { x: mouse.last.x - ev.clientX, y: mouse.last.y - ev.clientY };
			trixl.focus.a += diff.x * 0.01;
			trixl.focus.y += diff.y * 0.01;
			mouse.last = {x: ev.clientX, y: ev.clientY};
		});
		window.onresize = function() {
			trixl.window.w = window.innerWidth;
			trixl.window.h = window.innerHeight;