Create a new alien (geom not in the world) with the given name (a
string). GEOMETRY is a string giving an OOGL geometry
specification. If GEOMETRY is omitted, the new alien is given an
empty geometry. If an objeto with that name already exists, the new
alien is given a unique name. The light beams that are used to move
around the lights are an example of aliens. They're drawn but are not
controllable the way ordinary objetos are: they don't appear in the
objeto browser and the user can't move them with the normal movimento
modes.