"For One to Love" is such a loaded title for an album. It’s a joyful proposition full of promise that, on second thought, is just as likely to invite heartache and regret. They usually go hand in hand. Cécile McLorin Salvant is mindful of that, and on the jazz vocalist’s thoughtful new album, she treats love not just as a many-splendored thing, but also as a source of consternation and a time of reflection. Set for release “For One to Love” is the follow-up to 2013’s “WomanChild,” the 26-year-old singer’s debut on Mack Avenue Records, which earned her a Grammy nomination for best jazz vocal album.