LUCKY IN LATHER: So, you like that rosemary-mint soap you regularly buy. If only it had more...vanilla. No, not vanilla. Thyme? Maybe that is it. Soaptopia, which has an olfactory-pleasing outpost in Mar Vista, wants to know your ideal combination. If what you suggest is a real stunner, you could win free soap for a year. And not only do we all like free soap, but it is a free thing we all actually could use. CONTEST ENDS WEDNESDAY, MARCH 31: Get the delightful details here. Now: lavender + lime? Or lavender + lime + milk..?