Another congressional USC citation style

[whitesided]

In Senate 2238 we've found another code reference style. Specifically in sec 8, subsection (c):

No aircraft operated by an air carrier that holds an air carrier certificate 
issued under chapter 411 of title 49, United States Code, may take any 
action that implies recognition of the sovereignty of the Russian 
Federation over Crimea or its airspace.

As it turns out, looking back at our corpus of previously marked up items, this is pretty common, as is unpredictable capitalization:

title 18, United States Code
Title 17 Section 105 of the United States Code
section 1201(a) of title 17, United States Code
Section 711 of title 31, United States Code
Section 716(a) of title 31, United States Code

It looks like this is also similar to a notation style used for the CFR that konklone mentions over in issue #12

[konklone]

We actually do recognize this sentence structure for cites mentioning sections, but not for those mentioning only chapters. Chapters are parents of sections -- chapters can contain many sections. So sections are far more precise, and chapter cites are a lot less common than section cites, and I'm also not sure how best to represent a chapter cite (as in, create a unique ID for it) that doesn't conflict with a section cite. You can see me starting and then stopping to care twice, in #6 and #38.

I'm open to ideas for how to handle chapter cites elegantly!