Charles Laquidara is having second thoughts about participating in the four-day farewell to WBCN that starts tomorrow morning. The legendary former disc jockey, a centerpiece of the marathon sendoff, is upset that former jock Mark Parenteau is not invited to take part. “Mark’s one of the key figures, and we’re not allowed to mention him. His name’s been wiped out,’’ said Laquidara, who hosted “The Big Mattress’’ show back in the day. “I feel like a whore and a hypocrite doing [the farewell] because it’s not being handled in the ’BCN spirit.’’ After 40 years, the station is about to...