[main] Disconnect from tty when hiding splash

We were still processing keystrokes when the splash screen was
hidden. This caused problems because the tty is used by other
programs at that time.

src/main.c

@@ -549,6 +549,8 @@ remove_displays_and_keyboard (state_t *state)
       node = next_node;
     }
 
+  ply_keyboard_stop_watching_for_input (state->keyboard);
+  ply_keyboard_free (state->keyboard);
   state->keyboard = NULL;
 }