reconfigure({ locale, numberingSystem, conversionAccuracy, matrix } = {}) {
    const loc = this.loc.clone({ locale, numberingSystem });
    const opts = { loc, matrix, conversionAccuracy };
    return clone(this, opts);
  }
"Set" the locale and/or numberingSystem.  Returns a newly-constructed Duration.
@example dur.reconfigure({ locale: 'en-GB' })
@return {Duration}