References to hidden composite replacements are not hidden

[dqnykamp]

For many (if not most) composite components, references to their replacements are not hidden when the composite itself is not hidden. Presumably the references should also be hidden.

For example, in the below DoenetML, every reference to a hidden replacement is displayed.

<p>
  hidden originals:
  <group assignNames="a" hide><text>hi</text></group>
  <intersection assignNames="b" hide>
    <line>y=x</line><line>y=1-x</line>
  </intersection>
  <map assignNames="(c)" hide>
     <template><text>a</text></template><sources><number /></sources>
  </map>
  <samplePrimeNumbers assignNames="d" hide />
  <sampleRandomNumbers assignNames="e" hide />
  <select assignNames="f" hide>a b c</select>
  <selectFromSequence assignNames="g" hide />
  <selectPrimeNumbers assignNames="h" hide />
  <selectRandomNumbers assignNames="i" hide />
  <sequence assignnames="j" hide />
  <shuffle type="math" assignNames="k" hide>x y z</shuffle>
  <sort type="math" assignNames="l" hide>z y x</sort>
  <substitute match="x" replacement="y" assignNames="m" hide> x^2 </substitute>
</p>
<p>references are not hidden: $a, $b, $c, $d, $e, $f, $g, $h, $i, $j, $k, $l, $m</p>