math support: section title is cut off at the first `*-formula`

[pkra]

Something like

<title>
       Titles with math are cut off at the first
            <inline-formula content-type="math/tex">
                <tex-math>{\mathbb N}^2 \times {\mathbb R}</tex-math>
            </inline-formula> equation.
</title>

Will render

 Titles with math are cut off at the first

A sample JATS file can be found at https://gist.github.com/pkra/db08cf423cc1a5aa8eb7

[obuchtala]

Fixed.