patch 8.0.1639: libvterm code lags behind master

Problem:    Libvterm code lags behind master.
Solution:   Sync to head, solve merge problems.
diff --git a/src/version.c b/src/version.c
index 3a5bcfb..4b43e49 100644
--- a/src/version.c
+++ b/src/version.c
@@ -767,6 +767,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1639,
+/**/
     1638,
 /**/
     1637,