patch 8.2.0844: text properties crossing lines not handled correctly

Problem:    Text properties crossing lines not handled correctly.
Solution:   When saving for undo include an extra line when needed and do not
            adjust properties when undoing. (Axel Forsman, closes #5875)
diff --git a/src/version.c b/src/version.c
index 349ecbe..2a33137 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    844,
+/**/
     843,
 /**/
     842,