Punxsutawney Phil may not agree, but we’re getting ready for spring with two beloved small-ensemble masterworks. Franz Schubert’s warmly captivating Octet for winds and strings, and the original 13-instrument version of Aaron Copland’s ballet for the Martha Graham dance company, Appalachian Spring. (Actually this work, originally titled Ballet for Martha, was inspired by neither spring nor Appalachia. And old Phil really has no idea whatsoever. But we won’t tell.)