Updated Custom item sell #2

[FEATURE] Now custom items can be shipped.
[FEATURE] You can sell custom items with durability and they will be treated as different if used. This will avoid an user buying an item, using it then sell it back to store.

[BUGFIX] Shipping items will not remove them from the shopping cart, duplicating it.
[BUGFIX] Shipped tools will have their durability set to 0.
[BUGFIX] Spaces in description when adding prices are not considered.
[BUGFIX] ID saved in prices.xml has too much information.

-- Code related changes
[UPDATE] Long if-else chains whit strings were replaced with Switch(String) where possible.
[UPDATE] When adding a price for tools their durability will be considered as a difference factor. Hash for meta is calculated with this formula: (metahash + (durability * price))*price 


[DOCUMENTATION] Added lines of documentation for some methods. This is a preliminar add, the next ones will be added in future commits.