patch 8.0.0396: 'balloonexpr' only works synchronously

Problem:    'balloonexpr' only works synchronously.
Solution:   Add balloon_show(). (Jusufadis Bakamovic, closes #1449)
diff --git a/src/version.c b/src/version.c
index 796162b..0c9731d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    396,
+/**/
     395,
 /**/
     394,