patch 7.4.918

Problem:    A digit in an option name has problems.
Solution:   Rename 'python3dll' to 'pythonthreedll'.

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    918,
 /**/
     917,
 /**/