At about 12 minutes, "Kinah" isn't a particularly long piece.But it's been a long time coming for Detroit Symphony Orchestra music director Leonard Slatkin."Kinah" is the Hebrew word for elegy, and the composition - which the DSO premieres on Dec. 5 and 6 - is, in fact, Slatkin's memorial to his late parents, Felix, a violinist, and Eleanor, a cellist.