MapElement: revert clear(), #735

vtm/src/org/oscim/core/MapElement.java

@@ -114,7 +114,6 @@ public class MapElement extends GeometryBuffer {
 
     @Override
     public MapElement clear() {
-        labelPosition = null;
         layer = 5;
         super.clear();
         return this;

vtm/src/org/oscim/tiling/source/mapfile/MapDatabase.java

@@ -963,6 +963,8 @@ public class MapDatabase implements ITileDataSource {
 
                 if (labelPosition != null && wayDataBlock == 0)
                     e.setLabelPosition(e.points[0] + labelPosition[0], e.points[1] + labelPosition[1]);
+                else
+                    e.labelPosition = null;
 
                 mTileProjection.project(e);