sequence function: clone

    description:
        clone(sp, sp)
        clone(|x>, |y>), copies rules from |x> and applies them to |y>

    examples:
        -- set the context:
        context clone example
        
        -- learn some knowledge:
        age |Sarah> => |31>
        mother |Sarah> => |Jane>
        father |Sarah> => |Rob>
        
        -- clone |Sarah> to |Emma> (eg, they are twin sisters)
        clone(|Sarah>, |Emma>)
        
        -- show what we now know:
        dump
            ----------------------------------------
             |context> => |context: clone example>
            previous |context> => |context: global context>
            
            age |Sarah> => |31>
            mother |Sarah> => |Jane>
            father |Sarah> => |Rob>
            
            age |Emma> => |31>
            mother |Emma> => |Jane>
            father |Emma> => |Rob>
            ----------------------------------------

    see also:
        inherit
        
    TODO:
        test it works with superpositions, as claimed