Control colors of a data structure

[danielytics]

I'm using datascope to visualise data structures in clojure talks and it would be useful to be able to highlight subsections of the data structures. For example, metadata could be used for a nodes background color or other styling information.

So, something like

{:foo ^{:fill "#ff0000"} [1 2 3]}

Would render the [1 2 3] with a red background.

I'd be happy to take a stab at it myself if I'm given a little direction (as I don't know anything about DOT), if this is something you're interested in adding.

[hlship]

It's been a busy couple of months since I've checked up on this. I'd be glad to accept a reasonable PR; it should be possible to merge in some styling details as we emit the nodes. Take a peek at Zach's libs for some inspiration.

[danielytics]

I'll give it a shot as soon as I've a little spare time.