Full inventory troubles

[Quallysus]

If a player picks up items, filling their inventory while in a trade, (assuming the player has items in the trade menu), on trade cancel, the items are entirely lost. Not dropped, just deleted.

Proposed solutions:

• Disable item pickups while a player is currently in a trade
• Drop items that are not able to be returned on trade cancels due to full inventories

How to reproduce:

1. Start a trade between 2 accounts, where at least one account has something to put in the trade
2. One account puts an item into the trade
3. An external account drops items into the player's inventory, filling it
4. The account without items in the trade cancels the trade, deleting the trade's items.