This name and the `headingStructure` name are a bit odd. It doesn't tell me anything about what the thing does, which to me is a sign that we can find a better name. See [this java-inspired rant](http://steve-yegge.blogspot.com/2006/03/execution-in-kingdom-of-nouns.html) about Noun-names for a more extreme version of my feelings on that.

I would go with either `StructuredHeadingsManager` or `StructuredHeadingsPlugin` as an alternative.