refactor ExtrusionRenderer

- extract tile specific parts to BuildingRenderer
- sort tiles by distance for compilation
- slow down fade out animation

vtm-android-example/src/org/oscim/android/test/SimpleMapActivity.java

@@ -15,7 +15,7 @@
  * this program. If not, see <http://www.gnu.org/licenses/>.
  */package org.oscim.android.test;
 
-import org.oscim.layers.tile.vector.BuildingLayer;
+import org.oscim.layers.tile.buildings.BuildingLayer;
 import org.oscim.layers.tile.vector.labeling.LabelLayer;
 import org.oscim.map.Layers;
 import org.oscim.map.Map;