patch 8.1.1959: when using "firstline" in popup window text may jump

Problem:    When using "firstline" in popup window text may jump when
            redrawing it. (Nick Jensen)
Solution:   Set 'scrolloff' to zero in a popup window. (closes #4882)
diff --git a/src/version.c b/src/version.c
index 14842cd..485af13 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1959,
+/**/
     1958,
 /**/
     1957,