Added a back button to the shop GUI as many users have reported that it's more user friendly this way. Depending on the inventory size it will either place the back button on the bottom left or in the bottom middle row.
https://gyazo.com/e2cca1ad88a76aefece13dcc4452a1ea

Also added an "update changer" this will be used to automatically update your data files if there is ever a change to them in a newer version. This is being tested this update to introduce 2 new nodes under each shop in the Shop.yml file.

Although it should work fine and not mess up any data, it is suggested that you make a copy of your Shops.yml file before loading the new jar onto your server.