make data file path for elevation path configurable via the UI

Conflicts:
	route-converter/src/main/resources/slash/navigation/converter/gui/RouteConverter_ar.properties
	route-converter/src/main/resources/slash/navigation/converter/gui/RouteConverter_cs.properties
	route-converter/src/main/resources/slash/navigation/converter/gui/RouteConverter_de.properties
	route-converter/src/main/resources/slash/navigation/converter/gui/RouteConverter_sk.properties