Problem with escaped characters in file name tests

[brandes-pq]

If a file name test starts with an escaped ?, * or TAB, a syntax error is thrown. Example:

# fox -p '~?'
<errors>
  <error code="SYNTAX_ERROR" msg="Unexpected text after expression end: ~?"/>
</errors>

Whereas this works:

# fox -p 'a~?'
<foxpathTree>
  <foxpath context="/Users/hauke/Projects/ParsQube/XML/foxpath" text="a~?">
    <foxStep axis="child" name="a~?" regex="^a\?$"/>
  </foxpath>
</foxpathTree>