Do not interpret placeholder symbols in regular expressions in C2

[Akron]

First fix #66!

When using the regular expression operator #REG(...) confusingly regular expression operators that are also placeholders will first be interpreted as placeholders before the regular expression is interpreted.
So #REG(B.?um) is translated to

{
  "@type": "koral:token",
  "wrap": {
    "@type": "koral:term",
    "foundry": "opennlp",
    "key": "B..um",
    "layer": "orth",
    "match": "match:eq",
    "type": "type:regex"
  }
}

The expected translation is

{
  "@type": "koral:token",
  "wrap": {
    "@type": "koral:term",
    "foundry": "opennlp",
    "key": "B.?um",
    "layer": "orth",
    "match": "match:eq",
    "type": "type:regex"
  }
}