Fix undefined issues (#4804)

inc/class_session.php

@@ -357,6 +357,8 @@ function load_guest()
 		$mybb->user['moderateposts'] = 0;
 		$mybb->user['showquickreply'] = 1;
 		$mybb->user['signature'] = '';
+		$mybb->user['sourceeditor'] = 0;
+		$mybb->user['subscriptionmethod'] = 0;
 		$mybb->user['suspendposting'] = 0;
 
 		// Has this user visited before? Lastvisit need updating?
@@ -371,7 +373,7 @@ function load_guest()
 			{
 				$mybb->user['lastactive'] = (int)$mybb->cookies['mybb']['lastactive'];
 			}
-			if($time - $mybb->cookies['mybb']['lastactive'] > 900)
+			if($time - (int)$mybb->cookies['mybb']['lastactive'] > 900)
 			{
 				my_setcookie("mybb[lastvisit]", $mybb->user['lastactive']);
 				$mybb->user['lastvisit'] = $mybb->user['lastactive'];

newreply.php

@@ -1184,6 +1184,7 @@
 	}
 
 	// If the user is logged in, provide a save draft button.
+	$savedraftbutton = '';
 	if($mybb->user['uid'])
 	{
 		eval("\$savedraftbutton = \"".$templates->get("post_savedraftbutton", 1, 0)."\";");

newthread.php

@@ -1032,6 +1032,7 @@
 		$attachbox = '';
 	}
 
+	$savedraftbutton = '';
 	if($mybb->user['uid'])
 	{
 		eval("\$savedraftbutton = \"".$templates->get("post_savedraftbutton", 1, 0)."\";");