Save preserves invlets better.  Cannot reassign invlets from inventory
items anymore.  You can clear an invlet by pressing space, but it doesn't
really work because a restack() call aggressively assigns invlets, and we
immeiately restack().  So that's life unless someone tackles that code.
Fixed a strange bug where multidrop would try to takeoff an item that
didn't exist (resulting in a spurious message).