updated for version 7.4.684

Problem:    When starting several Vim instances in diff mode, the temp files
            used may not be unique. (Issue 353)
Solution:   Add an argument to vim_tempname() to keep the file.

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    684,
 /**/
     683,
 /**/