awful.autofocus: Also react on "tagged" signal (FS#883)

Apparently some people start a timer, switch to an empty tag and then let the
timer move a client to that empty tag. This change makes sure that this new
client will get the input focus in this case.

Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/awful/autofocus.lua.in

@@ -37,6 +37,7 @@ end
 atag.attached_add_signal(nil, "property::selected", check_focus_screen)
 client.add_signal("unmanage", check_focus)
 client.add_signal("new", function(c)
+    c:add_signal("tagged", check_focus)
     c:add_signal("untagged", check_focus)
     c:add_signal("property::hidden", check_focus)
     c:add_signal("property::minimized", check_focus)