added turtle helper: combine

src/lib/turtle/Helper.hx

@@ -14,4 +14,16 @@ class Helper {
 
 		return Success(null);
 	}
+
+	public static function combine(steps:Array<Void->Outcome<Noise, String>>):Outcome<Noise, String> {
+		for (step in steps) {
+			var res = step();
+
+			if (!res.isSuccess()) {
+				return res;
+			}
+		}
+
+		return Success(null);
+	}
 }