equality of <subsetOfReals> objects (intervals vs tuples)

[rogness]

Copying/Pasting the minimal (non)-working example Duane came up with for this issue. It arose at the workshop when trying to do answer checking for an answer involving the union of two intervals. (@dqnykamp, feel free to edit the title to be more accurate.)

<p>
<math name="u1" createIntervals>(1,2) union (3,4)</math> 
<math name="t1">(1,2) union (3,4)</math>
<boolean>$u1 = $t1</boolean>
</p>