HELENA, Mont. — Jury selection began Monday in a lawsuit against Warren Buffett’s BNSF Railway over the lung cancer deaths of two people who lived in a small Montana town near the U.S.-Canada border where thousands of people were exposed to asbestos from a vermiculite mine.The widespread contamination over decades led the U.S. Environmental Protection Agency in 2009 to declare the first-ever public health emergency during a Superfund cleanup. The Libby, Montana, site is one of the deadliest under the program …