Reported by k2: tipping one container's contents directly into
another container allowed transferring a wand of cancellation (not
mentioned: or a bag of holding or a bag of tricks) into a bag of
holding without blowing it up.
That's now fixed. There are other issues that this doesn't touch:
I think it's odd that you can transfer stuff from one carried
container to another but not from a carried container to a floor
container nor from one floor container to another one at same spot.
I didn't test shop billing so an not sure what happens when #tip
blows up a bag of holding and there are some unpaid items involved.
Using #tip on horn of plenty treats it like a container, but doing
that when it's carried doesn't offer the chance to tip its contents
directly into a carried container.
Tipping a carried container does not require free hands or even
limbs (for playability) but tipping such into another container
should require at least one free hand.
Fixes#872
7ae4efb07c