Make Looking Glass JSON roundtrip

[ramirez7]

Right now, we lose information such as the color of the nodes. If we preserve those through transformations, then things like filtering etc could also be subcommands in addition to options during generation.

[ramirez7]

Alternatively, maybe our main format should just be one we own.

[dustin]

Yeah, in an older version, there was a bit more structure, but it didn't seem necessary. Building some values that can contain attributes again independently of the links is doable. It could also just be a sparse node-attributes map and maybe an edge map. Otherwise, fall back to the Data.Graph inspired design.

[dustin]

The looking glass stuff is getting just a bit weird. It's got a set of attributes attached per-node, but the color isn't one of them. It wouldn't be hard to special case that, I guess.

There's also the title, which would could store as an attribute of "" as the overall document. Kind of a hack, but Doing It Right seems like a lot of work that doesn't really help all that much.