Light and bright with just enough sweetness, this carrot and cabbage slaw is practically designed for outdoor dining.  As an accompaniment to the main dish, it makes a plate more beautiful and lends some tang.  Include it in a picnic spread, and it livens up the rest of the offerings.  For subtle variations in raw carrot flavor and the most gorgeous assemblage of vegetables, opt for a bunch of rainbow carrots or make your own mix with varieties such as atomic red (my favorite), solar yellow, and cosmic purple. In place of the raisins which often appear in a carrot slaw, this recipe includes chopped pitted dates for a more…