Marylhurst, an independent institution near Portland, Ore., announced this month that it would close after 125 years, with its leaders saying they preferred it to die with dignity than limp on. The Board of Trustees plans to return the campus to the religious order that founded the college.  As is common when colleges close, faculty members, students and some alumni have objected to the decision and are urging the university's leaders to reconsider. They have questioned, among other things, how a university that was ahead of its time in its focus on adult students and its embrace of innovative approaches to learning lost its way.