Demo select-by-ID in dynamic callbacks

This is an awesome use case for dynamic callbacks - worthy of a demonstration:

SceneJS.material(
    function(data) {
        var updates = data.get("updates");
        if (updates && updates["materials"]) {
            var mat = updates["materials"];
            this.setBaseColor(mat.baseColor);
        }
    },
    // Subnodes...
)