While its long-awaited novel drug to treat Parkinson's disease inches closer to the finish line, Impax Laboratories (IPXL) has found other ways to keep its growth engine humming. Products treating migraine headache and attention deficit hyperactivity disorder, or ADHD, have recently led the way. Revenue from the two treatments powered Impax's second-quarter results, which in turn lifted shares more than 8% July 31, the day of the report, to over