Store datetime in UTC format now, and fix presentation of TZUTC. Also standardise message summaries on Notifications

app/Classes/FTN/Message.php

@@ -233,7 +233,7 @@ class Message extends FTNBase
 		$o->mo->from = $o->header['user_from'];
 		$o->mo->subject = $o->header['subject'];
 
-		$o->mo->datetime = $o->datetime;
+		$o->mo->datetime = $o->datetime->clone()->utc();
 		$o->mo->tzoffset = $o->datetime->utcOffset();
 		$o->mo->flags = $o->header['flags'];
 		$o->mo->cost = $o->header['cost'];

app/Classes/FTN/Packet.php

@@ -361,7 +361,7 @@ abstract class Packet extends FTNBase implements \Iterator, \Countable
 
 		$this->content .= "\00\00";
 
-		$this->messages = $msgs->map(fn($item)=>$item->only(['id','datetime']));
+		$this->messages = $msgs->map(fn($item)=>$item->only(['id','date']));
 
 		return $this;
 	}

app/Classes/FTN/Packet/FSC39.php

@@ -65,7 +65,7 @@ final class FSC39 extends Packet
 	 */
 	protected function header(Collection $msgs): string
 	{
-		$oldest = $this->messages->sortBy('datetime')->last();
+		$oldest = $this->messages->sortBy('date')->last();
 
 		return pack(collect(self::HEADER)->pluck(1)->join(''),
 			$this->fftn_p->node_id,				// Orig Node

app/Classes/FTN/Packet/FSC48.php

@@ -65,7 +65,7 @@ final class FSC48 extends Packet
 	 */
 	protected function header(Collection $msgs): string
 	{
-		$oldest = $msgs->sortBy('datetime')->last();
+		$oldest = $msgs->sortBy('date')->last();
 
 		return pack(collect(self::HEADER)->pluck(1)->join(''),
 			$this->fftn_p->node_id,				// Orig Node