While the months of January and February are usually down times on Broadway, Sony’s Masterworks Broadway is keeping things going during the winter by announcing a quartet of musical theater titles to be released between now and March. The most expansive release, due February 26, is another entry in Sony’s long-running Essential series: The Essential Stephen Sondheim.  Sondheim, of course, needs no introduction to musical theater aficionados.  Perhaps the most acclaimed theatrical composer and lyricist of the past 50-60 years, his breathtaking canon includes shows ranging from shows like West Side Story…