Vim-patch 8.0.0300 (#7258)

vim-patch:8.0.0300

Problem:    Cannot stop diffing hidden buffers. (Daniel Hahler)
Solution:   When using :diffoff! make the whole list if diffed buffers empty.
            (closes vim/vim#736)

25ea054458

src/nvim/version.c

@@ -652,7 +652,7 @@ static const int included_patches[] = {
   // 303,
   // 302,
   // 301,
-  // 300,
+  300,
   // 299,
   // 298,
   297,