Add: 1. New api in ShopManager allow devs get loaded shops.
2. Unload all loaded shops when server shutting down.
3. Add "Stupid Detector", if users download wrong jar from Github, plugin will told user.
4. Add "Database Fixer", if shop record in database is broken, plugin will skip that shop loading.
5. New "ShopClickEvent", allow you listen shop click!
Fix: 1. Some bugs.
2. Shop won't check their container exists, this may cause ghost shop on the world if use WorldEdit or /setblock remove the shop.
Changes: 1. Shops will save the changes when it unloading.