patch 8.1.1113: making an autocommand trigger once is not so easy

Problem:    Making an autocommand trigger once is not so easy.
Solution:   Add the ++once argument.  Also add ++nested as an alias for
            "nested". (Justin M. Keyes, closes #4100)

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1113,
 /**/
     1112,
 /**/