This operation is a bit ambiguous; it's not clear whether it
should return the bucket or the first item in the bucket, so
I'm just getting rid of it completely.
Returns the chance the object should wind up in a bag,
which can be overridden by a subclass, or by simply setting
an int "bag-chance" property on the object.
Returns the first object in the chain, e.g. the glowstones,
or fire elemental, or lighting bolt spell piece, which contains
this MovableLightSource in its property list.
The default implementation for non-rectangular objects is to
compute the bounds from the location list on each call, so we
can speed it up by figuring it out ourselves when we move.
Checks the list of Commands who have registered this command
with the map, and returns the first one whose rectangle of
interest intersects the agent issuing the command.
Checks the list of Commands who have registered this command
with the map, and returns the first one whose rectangle of
interest contains the agent issuing the command.