#42 Problem rendering equation located directly in "semantic" tag

[Radu Coravu]

If an equation is located directly in a "semantic" node (which also has an annotation), it is not properly rendered. Placing it inside a "mstyle" element fixes the problem.
The MathML sample can be found below:

        <!DOCTYPE math PUBLIC "-//W3C//DTD MathML 2.0//EN" "http://www.w3.org/Math/DTD/mathml2/mathml2.dtd">
        <math>
            <semantics>
                <mtext>NPH recovery rate=</mtext>
                <mfrac>
                    <mrow>
                        <msub>
                            <mrow>
                                <mtext>NPH grading</mtext>
                            </mrow>
                            <mrow>
                                <mtext>postoperative</mtext>
                            </mrow>
                        </msub>
                        <mo>-</mo>
                        <msub>
                            <mrow>
                                <mtext>NPH grading</mtext>
                            </mrow>
                            <mrow>
                                <mtext>preoperative</mtext>
                            </mrow>
                        </msub>
                    </mrow>
                    <mrow>
                        <msub>
                            <mrow>
                                <mtext>NPH grading according to Kiefer [2]</mtext>
                            </mrow>
                            <mrow>
                                <mtext>preoperative</mtext>
                            </mrow>
                        </msub>
                    </mrow>
                </mfrac>
                <mo>×</mo>
                <mn>10</mn>
                <annotation encoding="TeX">\hbox{NPH recovery rate=}{{\hbox{NPH
                    grading}}_{\hbox{postoperative}}-{\hbox{NPH
                    grading}}_{\hbox{preoperative}}\over{{\hbox{NPH grading according to Kiefer
                    [2]}}_{\hbox{preoperative}}}}\times 10</annotation>
            </semantics>
        </math>