[delds]

I have had trouble copying threads from old threads in phpbb2 to vbulletin, had trouble running import rotuines, so this helps me changing the timestamp back to the orginal post date, which is much easilier than editing the date than to go into the hosts sql manager and find the correct thread records and change the appropriate fields.

I assume this will also update lastposter / timedate fields as well as firstposter / datestamp fields which affect the forums thread list.