While my husband David was out of town, I had a chance to get caught up on a few shows that were spooled up in TiVo, ready to watch. One of these was HBO’s Treme, and I had the chance to watch the first three episodes all at once. When I came up for air, I felt like I’d been dunked in the floodwaters and come up a new person. Treme is densely layered, and cultural associations are thrown out offhandedly in practially every line, every scene. What did the comments about the different kinds of music mean? What was…