Fixed the attack function, some refactoring.

Wrote most of the attack function, but doesn't work yet. ...

The call to remove-object-attribute still gives problems, and I'm
running into trouble with the fact that monsters are stored by name
in each place, when really they need to be stored by value.

Started implementing trading system (buying works now). ...

Also added UI for creator.lisp and other minor changes.

Implemented about/talk/clear commands. ...

Also expanded the test world. Plus, I have now broken the 1000 line barrier! :-)

Implemented item pickup/dropping/equipping. ...

Also expanded the test world and some other adjustments.

Refactored define commands, started integrating monsters into the game world.