Adjust elements and plaintext
- Add Math element
- Change Table/Hatnote to more specific Infobox, Wikitable, Navigation, Messagebox, Note
- Update plaintext to not track transclusion (poor proxy)
- Update plaintext to instead track paragraph relation and the new elements (better proxy)
Addresses #121 (closed) (reorg of classes), #116 (closed) (now correctly extracting navboxes), #43 (closed) (ignore transclusion -- use other, better indicators), #42 (closed) (split by sections and paragraphs can be easily split by \n
as shown in get_first_paragraph
)