Make fields final if possible to ensure immutability

src/main/java/appeng/hooks/MeteoriteWorldGen.java

@@ -62,7 +62,7 @@ final public class MeteoriteWorldGen implements IWorldGenerator
 		final int x;
 		final int z;
 		final World w;
-		int depth;
+		final int depth;
 
 		public MeteoriteSpawn(int x, int depth, int z, World w) {
 			this.x = x;