Included patch for persistent undo.  Lots of changes and added test.
diff --git a/src/eval.c b/src/eval.c
index 446df8e..3c238fc 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -11869,6 +11869,9 @@
 	"perl",
 #endif
 #endif
+#ifdef FEAT_PERSISTENT_UNDO
+	"persistent_undo",
+#endif
 #ifdef FEAT_PYTHON
 #ifndef DYNAMIC_PYTHON
 	"python",