version 4.7
*  removed use of php's date_default_timezone_set() as wordpress wants everything to stay in UTC (despite having timezone in settings).  Checked and updated all DateTime create calls to ensure that they either cloned existing dates & ths their zones, or explicitly used a global timezone got from the saved wordspress timezone.
*  fix: small bug where if rdates (specific recurrence dates not due to rules) existed, then DTSTART was not propoerly included.
*  cope a bit better with ics files that seem ok but have junk in them - ignore junk events with empty dates.
*  improved formatting of some attachments
*  tested with version 3.1 of amr-events

git-svn-id: https://plugins.svn.wordpress.org/amr-ical-events-list/trunk@936881 b8457f37-d9ea-0310-8a92-e5e31aec5664