patch 8.0.0804: terminal window functions not yet implemented

Problem:    Terminal window functions not yet implemented.
Solution:   Implement several functions. Add a first test. (Yasuhiro
            Matsumoto, closes #1871)
diff --git a/src/version.c b/src/version.c
index 44ae124..86e8cc6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    803,
+/**/
     802,
 /**/
     801,