It’s a seasonal ritual that countless families enjoy — getting dressed in their holiday finest and heading off to see a local production of the “The Nutcracker,” that candy-coated ballet that celebrates all things Christmas. It’s also a ritual that’s critical to the bottom line of many dance companies, which depend on those solid “Nutcracker” sales to get them through the rest of the year. In fact, one prominent company, the Atlanta Ballet, told me that 70% of its annual box-office revenue derives from its production of the holiday favorite