v0.7.3a: fixed all darts incorrect being consumed when tipping all

SPD-classes/src/main/java/com/watabou/noosa/Tilemap.java

@@ -85,6 +85,16 @@ public class Tilemap extends Visual {
 
 		updateMap();
 	}
+	
+	public Image image(int x, int y){
+		if (!needsRender(x + mapWidth*y)){
+			return null;
+		} else {
+			Image img = new Image(texture);
+			img.frame(tileset.get(data[x + mapWidth * y]));
+			return img;
+		}
+	}
 
 	//forces a full update, including new buffer
 	public synchronized void updateMap(){
@@ -254,6 +264,6 @@ public class Tilemap extends Visual {
 	}
 
 	protected boolean needsRender(int pos){
-		return true;
+		return data[pos] >= 0;
 	}
 }