mglyph_aspect

an mglyph doubled preserving aspect ratio.

W3C sample	WIRIS
	$+ +$

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mi>
    <mglyph width="2" height="2" src="nist.png" alt="NIST"/>
  </mi>
  <mo>+</mo>
  <mi>
    <mglyph width="2" src="nist.png" alt="NIST"/>
  </mi>
  <mo>+</mo>
  <mi>
    <mglyph height="2" src="nist.png" alt="NIST"/>
  </mi>
</math>

Author: Bruce Miller