Add ability to specify the order of local transformations

[michael]

default order is:

1. translate
2. rotate
3. scale

uv.Actor.prototype.tWorld = function() {
  return uv.Matrix()
     .concat(this.tWorldParent())
     .translate(this.p('x'), this.p('y'))
     .rotate(this.p('rotation'))
     .scale(this.p('scaleX'), this.p('scaleY'));
};

[michael]

This could be solved by introducing transformation actors that can be combined in different ways (see Scene.js)

- Rotation
  - Translation
     - Scale
        - Rect
        - Text