patch 7.4.1707

Problem:    Cannot use empty dictionary key, even though it can be useful.
Solution:   Allow using an empty dictionary key.

src/version.c

@@ -748,6 +748,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1707,
 /**/
     1706,
 /**/