Fixed little problem with the join e quit.
Fixed NPE with the last saved location.

* Added per-world health separator
* Added per world hunger separator
* Added the possibily to teleport to the last location and not to the spawn.
* THE CHAT FORMAT HAS BEEN REMOVED AND FROM NOW ON BUNGEEWORLD WILL ONLY ISOLATE THE CHAT BETWEEN WORLDS, NO MORE THE FORMAT
* Completely rewrote most of the classes that will now be a lot optimized and bug-free
* Fixed several code bugs

[Fix] Fixed the NPE when leaving the server if no hub has been set.
[Fix] Fixed join and quit messages when not switching a world
[Fix] Fixed a save bug when leaving the server.
[Fix] Fixed a lot of bugs refering to the registerer system.
[Optimize] Optimized a lot the loading / saving method for player statistics
[Add] Added linked-worlds feature
[Add] Added the enderchest separator
[Add] Added new commands to manage the worlds.yml in game without having the risk of corrupting the file when manually editing it.

[Fix] Fixed the NPE when leaving the server if no hub has been set.
[Fix] Fixed join and quit messages when not switching a world
[Fix] Fixed a save bug when leaving the server.
[Fix] Fixed a lot of bugs refering to the registerer system.
[Optimize] Optimized a lot the loading / saving method for player statistics
[Add] Added linked-worlds feature
[Add] Added the enderchest separator
[Add] Added new commands to manage the worlds.yml in game without having the risk of corrupting the file when manually editing it.

[Fix] Fix the update-checker bug.
[Fix] Fixed the NPE bug when interacting with air or blocks