calendar 5.x-1.6

- 182998 Use Date API handling of timezones instead of Drupal default timezone offset when computing calendar values.
- 182155 Make sure multiple event nodes get a unique identifer when testing if they have already been processed.
- 181390 Cache_clear_all was missing wildcard in hook_cron().
- Add theme to override default Views handling of page title.
- Several fixes needed so menu tabs and arguments work on urls with $args in them, like node/$arg/calendar.
- Make sure plugin works even_empty, add install file that can clear cached calendar settings.
- Move administrative code to separate file so it isn't always parsed.
- Move plugin display themes to calendar.theme.
- Cache calendar fields() and calendar views() arrays.
- 172073 Allow for non-calendar arguments before any calendar arguments to dynamically filter calendar.
- Remove date fields from default view to force user to add the right field. Tired of handling support questions about unexpected date fields.
- 171306 keep empty nodes out of ical feed.
- 166659 and 160378 clean up handling of header and footer on empty pages.
- 155701 and 167110 ical and setup tabs sometimes didn't show up. Needed to rework the logic of calendar_is_calendar() and calendar_views() to properly identify views that have calendar types or calendar args.
- 159326 slight correction to indicating 'selected' day in mini calendar.
- 134240 fourth ical argument is optional, add '=NULL' so it will always work.
- 115144 make sure multiple day nodes don't get title and teaser created more than one time.
- 165845 make sure empty days have empty days theme.
- 167141 change array union to array merge to keep from losing first ical item.
- Stop adding label after node title in the default theme. Takes up too much space, and confuses people. Anyone that wants it there can do custom themeing.
- 171155 remove view-header from css, no longer being used.
- 176384 test for integer before checking calendar values.
- 175131 fix min height in IE6.
- 178839 get rid of use of 'Start' and 'End' in default themes. They sometimes show up when they shouldn't and take up too much room anyway. Anyone who wants them can add them back into a custom theme function.
- More cleanup of day and month themes.
- Check_markup was applied too many times to the day view, wiping out all html.
- Fixing the day view - view fields weren't getting added in correctly.
- 135296 Offset for date-specific timezone was using the offset field name instead of its value, so being ignored. This will fix problems where time was showing up in the calendar adjusted to GMT timezone.
- 160623 change event_get_offset() to date_get_offset() to match change in timezone.inc file.
- 138825 $view->all was not getting converted back to a number in the theme.
- 163552 fix inconsistency between integer values and zero-padded values in date formatting,
- 157393 make sure ical cache table isn't dropped if it was never created.