[FIX] calendar: fix get_range_domain to match all events.

In case of event not all day, the timezone has an impact.
So if we search for date >= 2016-01-31 (00:00:00) and that the current timezone
 is +5, we should search for date >= 2016-01-30 19:00:00.

date_to_str will drop the time.

This commit closes #12878
This commit closes #12971

addons/web_calendar/static/src/js/web_calendar.js

@@ -841,7 +841,7 @@ var CalendarView = View.extend({
      * between given start, end dates.
      */
     get_range_domain: function(domain, start, end) {
-        var format = time.date_to_str;
+        var format = time.datetime_to_str;
         var extend_domain = [[this.date_start, '<=', format(end)]];
         if (this.date_stop) {
             extend_domain.push([this.date_stop, '>=', format(start)]);