Bug in mouseConstraint

[trsh]

if (!mouse && engine && engine.render && engine.render.canvas) {
mouse = Mouse.create(engine.render.canvas);
} else {
mouse = Mouse.create();
Common.log('MouseConstraint.create: options.mouse was undefined, engine.render.canvas was undefined, may not function as expected', 'warn');
}

should be

if (!mouse && engine && engine.render && engine.render.canvas) {
mouse = Mouse.create(engine.render.canvas);
} else if(!mouse) {
mouse = Mouse.create();
Common.log('MouseConstraint.create: options.mouse was undefined, engine.render.canvas was undefined, may not function as expected', 'warn');
}