message() calls receive_message(mixed class, string message) in all
objects in the target list excluding those in the exclude list. This
basically tells the object the message.
Class is the type of message (used for clients and such). An example
would be 'combat', 'shout', 'emergency' etc.
Message is a string containing the text to send.
Target is a list of objects to be sent the message. This can be either
a single object string or object pointer, or may be an array of either.
If a target is non-living all objects in its environment will receive
Exclude is a list of objects that should not receive the message. This
can either be one object or an array of objects.