added cell for value and density

src/backend/Cell.java

@@ -15,4 +15,10 @@ public class Cell {
 	public int getDensity() {
 		return density;
 	}
+	public int setValue(int value) {
+		this.value = value;
+	}
+	public int setDensity(int density){
+		this.density = density;
+	}
 }