Field Gray by Philip Kerr (Putnam, $26.95, 435 pages, ISBN 978-0-399-15741-7) Have you ever thought about your dreams, noticed how real they seem when you’re asleep?  But then when you awake, it’s just in time to escape, or lose the elusive goal that’s always just out of reach?  That’s how mine end anyway.  But what if you couldn’t wake up?  What if your nightmare never ended?  What then?  How would