HEADED WESTAfter leaving Portsmouth, New Hampshire, the city where he was born and raised, Paul McDonough went first to Cambridge, Massachussets and then New York City, where his life as a photographer began in earnest. And while he never tired of New Yorks kaleidoscopic street scene, he felt the tug of the west, and of the sprawling, dreaming country that lay between the two coasts. From the 1960s through the 1990s McDonough made numerous photographic treks,