* Added flags to example backend to control its behaviour:

* Start with `-- -r` to run the reset plugin
  * Start with `-- -s` to run the state callback
* Rewrote yang dir load algorithm to follow the algorithm in [FAQ](FAQ(doc/FAQ.md#how-are-yang-files-found) with more precise timestamp checks, etc.

apps/backend/backend_main.c

@@ -596,7 +596,7 @@ main(int    argc,
 	if (yang_spec_parse_module(h, str, clicon_yang_module_revision(h),
 				   yspec) < 0)
 	    goto done;
-    /* 3. Load all modules in a directory */
+    /* 3. Load all modules in a directory (will not overwrite file loaded ^) */
     if ((str = clicon_yang_main_dir(h)) != NULL)
 	if (yang_spec_load_dir(h, str, yspec) < 0)
 	    goto done;