* move chart of accounts higher in document
* rewrite text a bit
* split controls to left-hand column
* remove dependencies between operations
* highlight result of last-applied operation (not very good looking atm)
* convert listickles to React widget
* add interactive hooks to introduction/definition paragraphs
* add highlighting to various items based on (2)
todo: ragged bottom edge using a SVG border-image?
After discussion with fp this probably isn't the direction (ish), but
want to checkpoint this in order to work on other stuff earlier in the
document, but not commit a single gigantic blob of stuff.
