Moving the handling of progress to GuiProgressBar

Adds an interface providing data for GuiProgressBar
Changed all containers simulating progress to implement the interface

src/main/java/appeng/container/interfaces/IProgressProvider.java

@@ -0,0 +1,32 @@
+package appeng.container.interfaces;
+
+import appeng.client.gui.widgets.GuiProgressBar;
+
+/**
+ * This interface provides the data for anything simulating a progress.
+ * 
+ * Its main use is in combination with the {@link GuiProgressBar}, which ensures to scale it to a percentage of 0 to
+ * 100.
+ *
+ */
+public interface IProgressProvider
+{
+
+	/**
+	 * The current value of the progress. It should cover a range from 0 to the max progress
+	 * 
+	 * @return An int representing the current progress
+	 */
+	int getCurrentProgress();
+
+	/**
+	 * The max value the progress.
+	 * 
+	 * It is not limited to a value of 100 and can be scaled to fit the current needs. For example scaled down to
+	 * decrease or scaled up to increase the precision.
+	 * 
+	 * @return An int representing the max progress
+	 */
+	int getMaxProgress();
+
+}