http_dav.c: added propfind callback for CALDAV:calendar-user-type
http_dav.c: added support for DAV:principal-property-search REPORT
reconstruct.c: Fix build issues with/without support for HTTP/DAV now that DAV DB changes occur in mailbox_update_indexes()
http_caldav.c: - correctly set Scheduling Inbox/Outbox flags even if the URL contains a resource
	       - only do scheduling delete processing on regular collections (NOT Scheduling Inbox)
http_caldav.c: rework the calendar component comparisons so we aren't doing more than required