Node dynamic config callbacks should execute on Node's scope

Nodes can be configured with callbacks, like this Rotate node that gets it's angle property off the data scope:

    SceneJS.rotate(function(data) {
        return { angle: data.get('pitch'), 1.0 };
    }

The mechanism within the nodes for converting the callback's result into properties is actually a bit of a runtime bottleneck on each node. Plus, it's no quite clear that whats going on in terms of what properties are actually being set on the node.

We could just call the callback on the Node scope, then just drive the node's setters inside of it, like this:

    SceneJS.rotate(function(data) {
         this.setAngle(data.get('pitch'));
         this.setX(1.0);
    },

Here we can see exactly where on the node each element of the data is going. Plus, we can flag node state updates inside node setters.