main: allow toggling all editor features when in view mode

Most of these toggles just change the appearance of things, and
all of them are harmless -- none of them modify the contents of
the buffer.

This fixes https://savannah.gnu.org/bugs/?54650.
Reported-by: Liu Hao <lh_mouse@126.com>

Bug existed since version 2.9.4, commit 54103d8e.

(The offending commit meant in the previous commit was 60f1090d.
My mistake.)

src/nano.c

@@ -1753,7 +1753,8 @@ int do_input(bool allow_funcs)
 	if (shortcut == NULL)
 		pletion_line = NULL;
 	else {
-		if (ISSET(VIEW_MODE) && !okay_for_view(shortcut)) {
+		if (ISSET(VIEW_MODE) && shortcut->func != do_toggle_void &&
+								!okay_for_view(shortcut)) {
 			print_view_warning();
 			return ERR;
 		}