Maine students who choose Colby will have new financial aid opportunities thanks to a grant from the Bernard Osher Foundation of San Francisco. The foundation awarded scholarship endowments totaling $4 million to provide funding for students from Maine attending Bates, Bowdoin, Colby or the University of Maine System. Each institution will receive $1 million to be used for undergraduate scholarships.     The endowments will enable a number of qualified students who have demonstrated financial need to enroll in the Maine institutions. The Osher Scholars will be selected by each institution. Those selected will retain the scholarship for all four undergraduate years provided that they maintain full-time status and good academic standing.     The Osher Foundation was established in 1977 by businessman Bernard Osher and his family to provide financial support for the arts, education, the environment, health care and social and community projects. Osher is a native of Biddeford, Maine, and a 1948 graduate of Bowdoin. He is the chairman of Butterfield & Butterfield Auctioneers, a San Francisco-based auction house.     "I grew up in Maine, and I know what a struggle it is for many Maine families and their talented sons and daughters to cope with the costs of college," Osher said. "It is gratifying to provide this endowment gift so that future generations will have this opportunity."