patch 7.4.1831

Problem:    When timer_stop() is called with a string there is no proper error
            message.
Solution:   Require getting a number. (Bjorn Linse)

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1831,
 /**/
     1830,
 /**/