message: Remove lookbehinds because Node 8 sucks
diff: @@ -84,9 +84,10 @@ export class MatrixEventProcessor {
  const matcher = escapeStringRegexp(member.user.username + "#" + member.user.discriminator) + "|" +
  escapeStringRegexp(member.displayName);
  const regex = new RegExp(
  - `(?<=${WORD_BOUNDARY})(${matcher})(?=${WORD_BOUNDARY})`
  + `(${WORD_BOUNDARY})(${matcher})(?=${WORD_BOUNDARY})`
  , "igmu");
  - body = body.replace(regex, `<@!${member.id}>`);
  +
  + body = body.replace(regex, `$1<@!${member.id}>`);
  }
  return body;
  }
  