calendar 6.x-2.2

Version 6.2.2
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- #429446 Col element must not be in thead.
- #506944 Localize more link in jcalendar popup.
- #529826 Add check_plain().
- #489722 Remove mistake that caused year calendar to process endlessly.
- #389294 Require the date field in calendar style, needed to identify what cell the date belongs in.
- #452690 Avoid errors when some date fields are empty (usually when there are multiple date fields in view.)
- #389294 Avoid errors when date argument or filter is not available as a date field.
- #454958 Calendar patch was broken in ical.
- #444526 Fix typo in variable name for calendar translation.
- #427996 More link logic was reversed.
- #389294 Avoid errors when date argument or filter is not available as date field.