void reset(flag)

Reset is called everytime the object is resetted. The first time is when
the object is loaded. If a room creates things when reset(), it should
check that these objects has moved out before creating new.

When reset is called for the first time, a null argument is passed. The
second time reset is called, flag will have vaule 1.

Every object will repetedly get resetted by a daemon. The game
wouldn't be fun if no challenges remained.