Operator symbols not shown in "simplified syntax trees"

[Kaljurand]

These outputs show the operator names:

csyntaxd     Output plain syntax trees as a Prolog list (for debugging).
csyntaxdpp Output plain syntax trees in pretty-printed form (for debugging).

but these do not:

csyntax            Output simplified syntax trees as a Prolog list.
csyntaxpp          Output simplified syntax trees in pretty-printed form.

E.g.

$ ./ape.exe -text "1 + 1 = 2." -csyntax -csyntaxd
<apeResult>
  <duration tokenizer="0.000" parser="0.023" refres="0.000"/>
  <syntax>[[specification,[formula,[expr,[int,1],[int,1]],=,[int,2]],'.']]</syntax>
  <syntaxd>[[specification,[formula,[expr,[int,1],[+],[int,1]],=,[int,2]],'.']]</syntaxd>
  <messages/>
</apeResult>

[tkuhn]

Fixed by c15a12e