Fix: Resolve deferred RelativeGeometries with cache

CityDoctorParent/CityDoctorModel/src/main/java/de/hft/stuttgart/citydoctor2/datastructure/ImplicitGeometryHolder.java

@@ -68,7 +68,7 @@ public class ImplicitGeometryHolder extends Geometry {
             RelativeGeometry relGeom = RelativeGeometry.of(gmlId);
             if (relGeom != null) {
                 ImplicitGeometryHolder igh = new ImplicitGeometryHolder(ig, relGeom);
-                CityObject parent = key.getParent();
+                CityObject parent = cache.get(key.getParent().getGmlId());
                 parent.removeGeometry(igh.getLod(), igh.getType());
                 parent.addGeometry(igh);
             } else {