context BUGFIX removing augs/devs

Always remove applied deviations/augments
in reverse order they were originally applied.

Fixes #462

src/context.c

@@ -1131,7 +1131,8 @@ lys_set_disabled(const struct lys_module *module)
     ctx_modules_undo_backlinks(ctx, mods);
 
     /* remove the applied deviations and augments */
-    for (u = 0; u < mods->number; u++) {
+    u = mods->number;
+    while (u--) {
         lys_sub_module_remove_devs_augs((struct lys_module *)mods->set.g[u]);
     }