message: Some DateTime changes
diff: @@ -466,37 +466,50 @@ bool DateTime::is_us_business_day () const throw () {
  const DatePartType m_day = dmonth (); // 1 - 31
  const DatePartType mon = month (); // JAN - DEC
  const WEEKDAY w_day = dweek (); // SUN - SAT
  + const DateType date_part = date(); // e.g. 20190110
  return (! (is_weekend () ||
  is_newyear () ||
  + // V-J Day. End of World War II (August 15-16, 1945)
  + //
  + (date_part == 19450815 || date_part == 19450816) ||
  +
  + // Assassination of President John F. Kennedy (November 22, 1963)
  + //
  + (date_part == 19631122) ||
  +
  // President Harry S. Truman day of mourning (December 28, 1972)
  //
  - (year () == 1972 && mon == DEC && m_day == 28) ||
  + (date_part == 19721228) ||
  // President Lyndon B. Johnson day of mourning (January 25, 1973)
  //
  - (year () == 1973 && mon == JAN && m_day == 25) ||
  + (date_part == 19730125) ||
  // New York City black out (July 14, 1977)
  //
  - (year () == 1977 && mon == JUL && m_day == 14) ||
  + (date_part == 19770714) ||
  // President Richard M. Nixon day of mourning (April 27, 1994)
  //
  - (year () == 1994 && mon == APR && m_day == 27) ||
  -
  - // World Trade Center attack (September 11-14, 2001)
  - //
  - (year () == 2001 && mon == SEP && m_day >= 11 && m_day <= 14) ||
  + (date_part == 19940427) ||
  // President Ronald Reagan day of mourning (June 11, 2004)
  //
  - (year () == 2004 && mon == JUN && m_day == 11) ||
  + (date_part == 20040611) ||
  // President Gerald R. Ford day of mourning (January 2, 2007)
  //
  - (mon == JAN && m_day == 2 && w_day == TUE && year () == 2007) ||
  + (date_part == 20070102) ||
  +
  + // President George H. W. Bush day of mourning (December 5, 2018)
  + //
  + (date_part == 20181205) ||
  +
  + // World Trade Center attack (September 11-14, 2001)
  + //
  + (year () == 2001 && mon == SEP && m_day >= 11 && m_day <= 14) ||
  // Martin Luther King Day (third Monday of January)
  //
  