Add blue light for fully empty Cells (#334)

src/api/java/appeng/api/implementations/tiles/IChestOrDrive.java

@@ -40,11 +40,13 @@ public interface IChestOrDrive extends ICellContainer, IGridHost, IOrientable
 	/**
 	 * 0 - cell is missing.
 	 *
-	 * 1 - green,
+	 * 1 - green, the cell is present and partially empty
 	 *
-	 * 2 - orange,
+	 * 2 - orange, the cell is present and full on types
 	 *
-	 * 3 - red
+	 * 3 - red, the cell is present and full on bytes
+	 *
+	 * 4 - blue, the cell is present but totally empty
 	 *
 	 * @param slot slot index
 	 *

src/api/java/appeng/api/storage/ICellInventory.java

@@ -123,6 +123,8 @@ public interface ICellInventory<T extends IAEStack<T>> extends IMEInventory<T>
 	 *
 	 * 3 - red, ( usually means the cell is 100% full )
 	 *
+	 * 4 - blue, ( usually means the cell is available and completely empty. )
+	 *
 	 * @return get the status of the cell based on its contents.
 	 */
 	int getStatusForCell();