In the largest gift ever given to the Northwestern University School of Law, Neil G. Bluhm and a charity group donated $15 million today to his alma mater. The gift will mostly be used to create new education initiatives and to “confront the serious predicament of student indebtedness,” Dean Daniel B. Rodriguez said. The largest portion of the gift is $6 million in unrestricted funds that can be used at Rodriguez’s discretion. The school will use $5 million to create an endowment in its Loan …