Multi-plugin unified menu (for GUI+ plugins)#146

A command to open a menu, which contains buttons to open the menus for AuctionGUI+, PlayerShopsGUI+, and ShopsGUI+ plugins.

• One command to unify all of the plugin GUIs, perhaps /market or something that doesn’t conflict with the three plugins.

• Ideally the button’s visibility would be customizable in-case user does not own all three plugins.

• Configurable hover text appears over each button.

• Alternatively, something more advanced that more tightly integrates the three interfaces of the plugins, but simpler is better IMO,