patch 8.1.1682: placing a larger number of signs is slow

Problem:    Placing a larger number of signs is slow.
Solution:   Add functions for dealing with a list of signs. (Yegappan
            Lakshmanan, closes #4636)
diff --git a/src/version.c b/src/version.c
index fff8d22..efcdb3f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1682,
+/**/
     1681,
 /**/
     1680,