patch 8.1.1558: popup_menu() and popup_filter_menu() are not implemented yet

Problem:    Popup_menu() and popup_filter_menu() are not implemented yet.
Solution:   Implement the functions. Fix that centering didn't take the border
            and padding into account.
diff --git a/src/version.c b/src/version.c
index f6bb71c..a59803b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1558,
+/**/
     1557,
 /**/
     1556,