- Popup footnotes: workaround strange behaviour of MuPDF
which is adding some unwanted margin above elements
with an "id=" attribute.
- In-page footnotes: also remove any left and right margin,
to keep footnotes aligned with the main text.
Also add 2 classnames (witnessed in quite a few recent
french books) to the list of classic classnames.
- Also bump crengine: CSS: fix parsing of multi classnames
and attributes selectors