patch 8.0.0504: looking up an Ex command is a bit slow

Problem:    Looking up an Ex command is a bit slow.
Solution:   Instead of just using the first letter, also use the second letter
            to skip ahead in the list of commands. Generate the table with a
            Perl script. (Dominique Pelle, closes #1589)
diff --git a/src/version.c b/src/version.c
index b6cc7d6..6719bf1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    504,
+/**/
     503,
 /**/
     502,