ol-ext: LayerSwitcher control
Add a simple popup layer switcher to the map. Only first level is enable in the popup.
The title or name layer's property is used to named the ol.layer in the switcher.
It shows use of the displayInLayerSwitcher layer's property to cause it to not display in the LayerSwitcher
The baseLayer layer's property manage exclusive visibility on layers (only one base layer is shown at a time).