Step 4.1

Big changes :
- Item dragger update, now correctly get the center of the item to
replace it. Improved performances, disabled right click.
- Characters are now in a seperate table.
- Items are now stored in items.json and can be query on
http://hostname::port/item/id_item, and supports JSONP.
- Inventory now checks for equipements slots restrictions, such as the
management of 1 handed and 2 handed weapons, and if the item can go in a
particulary slot.
- Item inspector partialy disgned. Comming soon, fixes about it.
- Texts for the client are now generated in texts.js
- Made some improvements about jQuery usage once again
- Now when a player logout/leave the page, it save correctly all off his
characters.
- Character pseudo availability is no longer case sensitive