Release bounds after usage.

src/engine/InterestManagement/HeightMap.java

@@ -255,6 +255,8 @@ public class HeightMap {
         float zoneArea = (heightMapZone.getBounds().getHalfExtents().x) *
                 (heightMapZone.getBounds().getHalfExtents().y);
 
+        blendBounds.release();
+
         float blendDelta = zoneArea - maxBlendArea;
         float currentDelta = zoneArea - currentArea;