Use InlineMathFragment when rendering/converting inline equations
There's something not quite right about the way the data for inline equations is currently handled, as the data is in several places: in the ProseMirror node, added to the HTML as
data-tex-representation, and separately in
This will need some investigation, but I think at least the
InlineMathFragment model should be updated when the content is edited (in the editable node view) and should be used when rendering the node view.