Christmas really does have 12 days. According to the traditional Christian calendar, Christmas Day marks the beginning of Christmastide and concludes with the celebration of Epiphany on Sunday. Foothill Children’s Chorus will mark the end of the Christmas season with a second performance of its repertoire on Sunday. Auditions for those interested in joining the premiere chorus also start this month in preparation for the group’s spring concert (see box). Epiphany is one of the important days on the church’s calendar, marking the visit of the three wise men to the young Jesus, said the Rev. Richard Johnson of Peace …