Steve Lehman and Orchestre National de Jazz Ex Machina Pi Recordings   Saxophonist Steve Lehman not only has chops as a jazz musician, he is a trained composer with a background in electronics. Ex Machina is his most ambitious project to date, with electronics developed at the premiere new music center IRCAM in Paris. They respond live in performance to the spectral harmonies and polyrhythms made by the orchestra. While live electronics have been emanating from IRCAM for some time, Lehman’s electronics are neatly incorporated into both composed and improvised textures.   The first track “39” contains a solo by