mtextSbg4

Tests setting mathbackground and foreground colors for <mtext>.

W3C sample	WIRIS
	$\text{Theorem 1:}$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mstyle mathbackground="blue" color="white">
    <mtext>Theorem 1:</mtext>
  </mstyle>
</math>

Author: Robert Miner and Jeff Schaefer, Geometry Technologies