Sets the Thing Type of a thing. There are different properties associated with each
thing type. Changing from one type to another will make the thing assume the properties of another type. Syntax:
SetThingType(thing, type);
For example, a property of the item type is no collision. You can walk right through them. Change a stormtrooper to
an item type and he will lose his collision. But then his AI will not function correctly.