Robert James Waller, whose best-selling, bittersweet 1992 romance novel “The Bridges of Madison County” was turned into a movie starring Meryl Streep and Clint Eastwood and later into a soaring Broadway musical, has died in Texas, according to a longtime friend. He was 77. Scott Cawelti of Cedar Falls said Waller died early Friday at his home in Fredericksburg, Texas.