Fixes flourishlib#220

Fixes an issue with how Microsoft Exchange (2010) and Outlook Web Access incorrectly handles some file attachment types and therefore cause the attachment to be seen as an inline attachment, but with no ability to recover the file from the body.

fMailbox.php

@@ -219,7 +219,7 @@ static private function handlePart($info, $structure)
 		}
 
 		// This indicates a content-id which is used for multipart/related
-		if ($structure['content_id']) {
+		if ($structure['content_id'] && $structure['disposition'] == 'inline') {
 			if (!isset($info['related'])) {
 				$info['related'] = array();
 			}