patch 9.0.0449: there is no easy way to translate a key code into a string

Problem:    There is no easy way to translate a string with a key code into a
            readable string.
Solution:   Add the keytrans() function. (closes #11114)
diff --git a/src/menu.c b/src/menu.c
index 014d051..6a93316 100644
--- a/src/menu.c
+++ b/src/menu.c
@@ -2890,7 +2890,7 @@
 			*menu->strings[bit] == NUL
 				? (char_u *)"<Nop>"
 				: (tofree = str2special_save(
-						  menu->strings[bit], FALSE)));
+					menu->strings[bit], FALSE, FALSE)));
 		vim_free(tofree);
 	    }
 	    if (status == OK)