Bug: option "layer" for a TreeNode does not support a layer's name anymore

[Skrol29]

Hi GeoExt Team !

In GeoExt version "pre-2.0", the property "layer" of a TreeNode configuration could be a layer's name instead of a the Layer object itself.

That was a welcome shorthand when the LayerTree composition comes from a JSON string, like when the attached store has an Ajax data source.

My workaround for now is to add a listener in the LayerTree's configuration:

var options = {
    ...
    listeners: {
        beforeitemappend: function (_this, node) {
            if (node.data.layer && (typeof node.data.layer == 'string') ) {
                var x = my_application.my_map.getLayersByName(layer);
                if (x.length > 0) {
                    node.data.layer = x[0];
                }
            }
        }
    }
}

The regression seems bogus, nevertheless the feature is hotly appreciable.
I can suggest a fix if needed but the snippet in GeoExt version "pre-2.0" was ok.

Code where the layer is fetched from the node configuration:
File: "/src/GeoExt/tree/LayerNode.js", line:

    init: function(target) {

        this.target = target;
        var layer = target.get('layer');

[Skrol29]

Can be fixed by issue #213 .

[marcjansen]

#213 should be made a PR, I added a comment over there.