If the idea that there is a Stevie Nicks vault filled with lost songs from the ‘70s is absolutely thrilling, her new album, 24 Karat Gold — Songs From the Vault, should give you joy. It’s also her first since 2011’s In Your Dreams and features a collection of lost demos, “reimagined”: “[W]e found all the songs that, somehow, were taken from my house or picked up or loaned out or whatever. I call them my 24 karat gold songs.” If there’s any doubt, listen to 24 Karat’s first single, “The Dealer,” which dates back to 1979 (Tusk!) and has that perfect “Gypsy” sound. Are there more shawls in the vault?