Sending items to players/between players

[fjallnari]

The requested feature doesn't sound that hard on paper, but it requires #108 to be completed first, with possibly character names being saved as well (to create a autocomplete whom to send the item to).

Sender would click a button in the item accordion to send an item -> small dialog with input/autocomplete whom to send it to -> possibly new Sockets event (send-item?) would fire up -> (maybe add a pop-up to accept or reject the item for the receiving player) -> remove the item from the original sheet & add it to the new owner. After that modifyCharacter would probably need to be triggered.