Better support for LayerGroup (support nested LayerGroups and automatic bounds computation) #34
Description
The current catalog.create_layergroup call doesn't properly support creating a layer_group containing layergroups since the
layers composing the layergroup are assumed to be only simple layers.
Moreover, when a None bounds is provided, the code will automatically set it to -180,-90,180,90 although GeoServer is able to automatically compute the LayerGroup actual bbox when a null bbox is provided. So it would be great to maintain that behavior.
A PR with code updates will be provided