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/hooks/MeteoriteWorldGen.java

@@ -19,7 +19,7 @@ import cpw.mods.fml.common.IWorldGenerator;
 final public class MeteoriteWorldGen implements IWorldGenerator
 {
 
-	class myGen implements ICompassCallback
+	static class MyGen implements ICompassCallback
 	{
 
 		double distance = 0;