Underneath a crisp sheath of pomegranate-glazed tempura pumpkin, a mélange of roasted pumpkin, avocado, and sushi rice come together in this seasonal roll.  Nectar–the Main Line’s French-Asian fusion monolith–is just as much about numbers as it is about food.  From the billowy 18-foot silkscreen Buddha tapestry that towers over the cavernous 200-seat dining room…