added test for multidimensional for loop

examples/test-commands.wt

@@ -95,5 +95,5 @@ set VARS2 = a, b, c, d
 set RESULT =
 for VARS1
   for VARS2
-    set RESULT = RESULTVARS1.VARS2;
-check RESULT = 1.a;1.b;1.c;1.d;2.a;2.b;2.c;2.d;3.a;3.b;3.c;3.d;4.a;4.b;4.c;4.d;
+    set RESULT = RESULTVARS1VARS2
+check RESULT = 1a1b1c1d2a2b2c2d3a3b3c3d4a4b4c4d