Some performance or memory optimizations

Replaced String concat in loops with StringBuilder (performance)
Replaced for with keySet + Map.get() through for with entrySet (perf)
Changed inner classes to static classes, mostly struct like (memory)

src/main/java/appeng/items/materials/ItemMultiMaterial.java

@@ -60,7 +60,7 @@ public class ItemMultiMaterial extends AEBaseItem implements IStorageComponent,
 		instance = this;
 	}
 
-	class SlightlyBetterSort implements Comparator<String>
+	static class SlightlyBetterSort implements Comparator<String>
 	{
 
 		final Pattern p;