SYNOPSIS:
        int set_light(int n)

DESCRIPTION:
        An object is by default dark. It can be set to not dark by
        calling set_light(1). The environment will then also get this
        light. The returned value is the total number of lights in
        this room. So if you call set_light(0) it will return the
        light level of the current object.
        
        Note that the value of the argument is added to the light of
        the current object.

BUGS:
	This handling of light by the parser is inappropriate for most
	purposes: If you put a burning candle into a safe, the safe
	will start to emit light.