ushort support

[pkra]

A random find: spmj1815 uses the ushort package.

Right now, e.g.,

$\ushort\alpha=\{\alpha_1,\dots,\alpha_k\}$

becomes

<inline-formula content-type="math/tex"><tex-math>\mathchoice{<inline-formula content-type="math/tex"><tex-math>\underline{{}}</tex-math></inline-formula>}{<inline-formula content-type="math/tex"><tex-math>\underline{{}}</tex-math></inline-formula>}{<inline-formula content-type="math/tex"><tex-math>\underline{{}}</tex-math></inline-formula>}{<inline-formula content-type="math/tex"><tex-math>\underline{{}}</tex-math></inline-formula>}\alpha =\{\alpha _1,\dots ,\alpha _k\}</tex-math></inline-formula>

which is broken in several ways.

[pkra]

Perhaps it's sufficient for now to map \ushort to \underline (or simply adjust the source).