Add option to force a subject when posting threads

inc/config.php

@@ -489,6 +489,8 @@
 	$config['force_body_op'] = true;
 	// Require an image for threads?
 	$config['force_image_op'] = true;
+	// Require a subject for threads?
+	$config['force_subject_op'] = false;
 
 	// Strip superfluous new lines at the end of a post.
 	$config['strip_superfluous_returns'] = true;
@@ -1232,6 +1234,7 @@
 	$config['error']['tooshort_body_op']	= _('OP must be at least %d characters long.');
 	$config['error']['no_body']		= _('The body was too short or empty.');
 	$config['error']['noimage']		= _('You must upload an image.');
+	$config['error']['nosubject']		= _('You must add a subject.');
 	$config['error']['toomanyimages'] = _('You have attempted to upload too many images!');
 	$config['error']['nomove']		= _('The server failed to handle your upload.');
 	$config['error']['fileext']		= _('Unsupported image format.');

post.php

@@ -641,7 +641,11 @@ if (isset($_POST['delete'])) {
 				error($config['error']['no_body']);
 			}
 		}
-	
+		
+		if ($post['op'] && $config['force_subject_op'] && $post['subject'] == '') {
+			error($config['error']['nosubject']);
+		}
+		
 		if (!$post['op']) {
 			// Check if thread is locked
 			// but allow mods to post