New options: keep/sell weapons/items

Merry Christmas and a Happy New Year! The Christkind has granted us two new game options:

Feature updates

• "Keep weapons/items on death": If this option is not activated, a tank will lose one copy per weapon/item when it dies. (Tanks which did not get a turn at all are spared.)
• "Weapons/items can be sold": If this option is not activated, purchased weapons/items can no longer be sold.