patch 8.0.0728: the terminal structure is never freed

Problem:    The terminal structure is never freed.
Solution:   Free the structure and unreference what it contains.
diff --git a/src/version.c b/src/version.c
index 77ff8c7..41b0690 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    728,
+/**/
     727,
 /**/
     726,