Configurability at last! Also lots of internal code optimizations and bug fixes for a much better and playable experience.
Changelog
+ Configurability for the following plugin settings has been added in the config.yml: Resource conversion, shield recipe, cobbler conversion, custom item recipes, welcome message, mob spawn buff, level restriction
+ Added leather as an item the /cc materials command will now give
+ Added a custom config file called data.yml to store data about players and their highest tiered items
+ /cc craft now alerts players when no cobblestone is available to convert in their inventory

* Command syntax has been changed to /cc [argument]
* /cc tools now requires a second argument that dictates what tier of gear the player will receive
* Much more internal code optimization
* Config.yml version will now be checked on startup
* Fixed a bug that broke the Anti-Stone Crown crafting
* Fixed a bug that broke the T5 and T8 shield crafting
* Fixed a bug where custom resources couldn't be upgraded using a crafting grid
* Fixed a bug where the T8 shield required 50 levels instead of 40 to use
* Fixed a bug where the T9 trident also launched rockets on right click
* Fixed a bug where repairing stone hoes and swords gave more durability than supposed to