Added feature, fixed bugs

- Fixed a shovel bug
- Fixed Multiworld Support (More than 12 plugins "break" HeavySpleef,
thanks to Puseidr)
- Fixed a NullPointerException with the signwall

* Recoded mysql database
* Recoded inventory menu
* Remade the inventory join menu
* Improvements for the anticamping feature
* /spleef start does not longer require an arena argument

+ Added flag to set the icon in the inventory join menu
+ Added flag to regenerate floors in an intervall