Christmas season is all about watching movies about family gatherings, which makes “Happiest Season” ideal for the occasion. It’s not perfect by any means, but it has enough charm and just the right actors to carry it through. Mackenzie Davis plays a young woman who agrees to bring her girlfriend (Kristen Stewart) to her family’s annual Christmas gathering. Problem is: she hasn’t come out to them yet, which leads to a series of unpredictable events. I don’t usually ask much from a Christmas movie. I want it to entertain me, and “Happiest Season” does exactly that. It does veer into cliche territory at times, but overall it has just the right dose of humor and drama to make it worth the price of admission. Stewart and Davis are both delightful, and they’re surrounded by a solid supporting cast as well. If this sounds like your cup of tea, then “Happiest Season” will more than satisfy you this Holiday season.