grc: switched to ToggleActions; made visibility settings persistent

(new pull request since to other one is closed)

> However, it would be useful to have the state of the report and search visibility shown as a check mark next to the menu entry, and change the menu entry to "Toggle ...".

Good point. I switched to ToggleActions as you suggested. Also, the toggle states are saved between sessions now. For the labels I prefer "Show...". I think it better go's with the check marks. Without the check marks "Toggle..." is better. What do you think?