[GeoLib::SimplePolygonTree] Using isPolylineInPolygon().

The until now implementation is not correct. Using
Polygon::isPolylineInPolygon(), which is tested already.

GeoLib/SimplePolygonTree.cpp

@@ -31,20 +31,7 @@ SimplePolygonTree::~SimplePolygonTree()
 
 bool SimplePolygonTree::isPolygonInside (const SimplePolygonTree* polygon_hierarchy) const
 {
-	const Polygon* polygon (polygon_hierarchy->getPolygon());
-	// check *all* points of polygon
-	size_t n_pnts_polygon (polygon->getNumberOfPoints() - 1), cnt(0);
-	for (size_t k(0); k < n_pnts_polygon && cnt == k; k++) {
-		if (_node_polygon->isPntInPolygon (*(polygon->getPoint(k)))) {
-			cnt++;
-		}
-	}
-
-	// all points of the given polygon are contained in the
-	if (cnt == n_pnts_polygon)
-		return true;
-	else
-		return false;
+	return _node_polygon->isPolylineInPolygon(*(polygon_hierarchy->getPolygon()));
 }
 
 void SimplePolygonTree::insertSimplePolygonTree (SimplePolygonTree* polygon_hierarchy)