increase non-TeX font-size a bit for paragraphs with TeXed-parts.

Note that the non-TeX-text is now larger than the TeX-ed text when
they were the same size before. Neither before nor after the change
both variants had the same baseline, thus making the TeX text look
out of place.

This patches increases the font size by one pixel. Please review
if this is enough for you liking. See #17