updated for version 7.2.420

Problem:    ":argedit" does not accept "++enc=utf8" as documented. (Dominique
            Pelle)
Solution:   Add the ARGOPT flag to ":argedit".

src/version.c

@@ -681,6 +681,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    420,
 /**/
     419,
 /**/