patch 8.0.0683: visual bell flashes too quickly

Problem:    When using a visual bell there is no delay, causing the flash to
            be very short, possibly unnoticeable.  Also, the flash and the
            beep can lockup the UI when repeated often.
Solution:   Do the delay in Vim or flush the output before the delay. Limit the
            bell to once per half a second. (Ozaki Kiichi, closes #1789)
diff --git a/src/version.c b/src/version.c
index c1d5ec8..a5f6f18 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    683,
+/**/
     682,
 /**/
     681,