By Caldwell Titcomb The Boston Lyric Opera (BLO) is currently offering Georges Bizet’s “Carmen,” his last completed and finest opera, which had its delayed and unsuccessful premiere in 1875. According to Opera America, “Carmen” ranks No. 4 in the list of most performed works from the 1880s to 2005, surpassed only by Puccini’s “Madama Butterfly”…