Make beamer botton adjust to button font

[samcarter]

Currently, the height of beamer buttons is hard coded in pt. It might be nice to use a font depended unit instead.

\documentclass{beamer}

\setbeamerfont{button}{size=\Huge}

\begin{document}
\begin{frame}
\beamergotobutton{Foo}
\end{frame}
\end{document}