patch 9.0.0307: :echomsg doesn't work properly with cmdheight=0

Problem:    :echomsg doesn't work properly with cmdheight=0.
Solution:   Improve scrolling and displaying.
diff --git a/src/version.c b/src/version.c
index b69b74a..80ce6fe 100644
--- a/src/version.c
+++ b/src/version.c
@@ -708,6 +708,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    307,
+/**/
     306,
 /**/
     305,