Next Open Hours feature

[Djuki]

Added feature to get next open hour for DateTime requested in #18

Example:

    $openingHours = OpeningHours::create([
        'monday' => ['09:00-11:00', '13:00-19:00'],
    ]);

    // 2016-09-26 13:00:00
    $nextTimeOpen = $openingHours->nextOpen(new DateTime('2016-09-26 12:00:00'));

Unit tests added for class OpeningHours but not for OpeningHoursForDay because it is also covered in the same tests.

There could be space for code improvement in method nextOpen, and I would like to improve it if you have some ideas.

New method nextOpen is documented and unit tested. Also, psr2 fixer is applied to the code changes.

[Djuki]

@freekmurze I came up with more readable and understandable solution for OpeningHoursForDay::nextOpen method. I can push if you think it could be an acceptable option.

public function nextOpen(Time $time)
{
    foreach ($this->openingHours as $timeRange) {
        if ($nextOpen = $this->findNextOpenInWorkingHours($time, $timeRange)) {
            return $nextOpen;
        }

        if ($nextOpen = $this->findNextOpenInFreeTime($time, $timeRange)) {
            return $nextOpen;
        }
    }

    return false;
}

private function findNextOpenInWorkingHours(Time $time, TimeRange $timeRange)
{
    if ($timeRange->containsTime($time) && next($timeRange) !== $timeRange) {
        return next($timeRange);
    }
}

private function findNextOpenInFreeTime(Time $time, TimeRange $timeRange, TimeRange &$prevTimeRange = null)
{
    $timeOffRange = $prevTimeRange ?
        TimeRange::fromString($prevTimeRange->end().'-'.$timeRange->start()) :
        TimeRange::fromString('00:00-'.$timeRange->start())
    ;

    if ($timeOffRange->containsTime($time)) {
        return $timeRange->start();
    }

    $prevTimeRange = $timeRange;
}

[sebastiandedeyne]

Sorry for the very late merge.

All looks good, thanks for your contribution!