EPD-190: add copy function to ObservedSettings
EPD-190: override copy() to produce more specific return type
EPD-190: update BottomPanel with new settings classes
EPD-190: update EncLayerFactory to query new settings classes
EPD-190: updates towards use of new settings classes
EPD-190: remove AisLayerCommonLocalSettings and AisLayerCommonGlobalSettings
EPD-190: refactored layer settings listeners such that these are (now again) stand alone interfaces rather than inner interfaces. Unfortunately this was needed in order to allow a settings class to implement its own listener interface (if the settings instance wants to obey to changes to another instance of the same class).