Striked fixed HHVM bug
Added Duration::getDays(), getHours(), getMinutes()
Added Interval::contains(), containsInstant(),
Added LocalDateTime::ofEpochSecond(), ofInstant(), toEpochSecond(), toInstant()
Added Interval::overlaps()
Added LocalDate::ofInstant(), LocalTime::ofInstant()
Added Interval::abuts()
Added Interval::isEqualTo()
Added Interval::overlap(), union()
Added Interval::__toString()
Added Instant::minOf(), maxOf()
Added Interval::gap()