Add 'continue' command for loops. Also enhance for() unit tests which are now breaking and need to be fixed

unittests/continue_while.chai

@@ -0,0 +1,14 @@
+var i = 0
+var j = 0
+
+while (i < 10) {
+  if (++i > 5)
+  {
+    continue
+  }
+
+  j = i;
+}
+
+assert_equal(10, i);
+assert_equal(5, j);