Compatibility with bdtpicker V4

Thank you. I will check your patch and the JS library to see what happened in the 4.x branch at weekend.
And I think I will start a new branch named "7.x-4.x"

This patch still does not work together with the "All Day" module.

The patch also doesn't work when there isn't any time picker present (date field collection only years, months and days). Also, the date picker was displayed far to the top of the date field. I wasn't able to capture it - date picker hides itself on any keypress.

Implemented features so far:

• sideBySide
• showTodayButton
• showClear
• showClose
• inline
• keepOpen (visible if inline is TRUE, and input field can be hidden)
• calendarWeeks
• viewMode
• daysOfWeekDisabled //Requires date_restrictions and weekdays modules
• minDate, maxDate //Requires date_restrictions module
  • Fixed date, e.g. 18-02-2017
  • Relative date, e.g. '-10 days', '+10 day' //requires interval module
  • Fixed date from a field in the host entity
  • Relative date from a field in the host entity, e.g. interval field set to '+10 day' //requires interval module

If host field is multivalued:

• value from [0] element will be taken for minDate (if restriction is configured)
• value from [last] element will be taken for maxDate (if restriction is configured)

This patch also fix "All Day" problem.

Patch in #7 works fine for me.

I add support module work_calendar

@madt: What does this line do?

$max_date = date_select_input_date($element['value'], array_merge($element['#restrictions']['max']['date'], array('hour' => 23, 'minute' => 59, 'second' => 59)));

@lazzyvn,
please open up a separate issue to add support for Work Calendar.