Fix normalize term case

[MaisaMilena]

normalize function wasn't working. I started to fix it in Issue-15 and updating it to reduce but still not working.

• [x] Check with Victor which fm.lang function is to be used
• [x] Fix it

---

Old code:

// Normalizes a definition
const normalize = (file: string, defs: fm.Defs, opts: fm.core.NormOpts) => {
  let norm : any;
  try {
    norm = fm.lang.show(fm.lang.norm(defs[file], defs, {}));
  } catch (e) {
    norm = "<unable_to_normalize>";
  }
  return norm;
}