Hal Ketchum is happily semi-retired in the Austin, Texas, area, so his swing through New England this weekend is a rare treat for fans of his genre-crossing music. As his heyday atop the country charts in the 1990s proved, Ketchum's music is a hybrid with plenty of folk, rock and soul elements coloring his music.Ketchum is playing Saturday night at the Spire Center in downtown Plymouth.