A) In this new update, you can add custom commands to be run in a shop. It also means that:
1. You can create multiple pages in a single shop, by adding the command to open the next shop!
2. Any command can be used, so you can sell something from other plugin, for example.
3. It's totally customisable. The item can either be totally normal or have lore, enchantments and custom names, that you can set with the two new commands.

B) Added /[rn|rename] [text] and /[sl|setlore] [line] [text], so you can make custom items.

C) Small code cleanup.