Stevie Tull was just 7 months old when he started to benefit from programs provided by Easterseals Delaware & Maryland’s Eastern Shore. And now, three decades later, they are an essential part of the life of the Seaford resident. Tull, 38, has Pelizaeus-Merzbacher disease, a rare neurological disorder that resembles cerebral palsy in its symptoms, said his father, Steve. Stevie …