Change illogical default of $config[force_body]

Makes JS and non-JS enforcement equivalent while providing a downgrade path.

JS may not allow empty bodies even when $config[force_body] false. Don't care enough to fix. PR welcome.

Close #493.

inc/config.php

@@ -497,7 +497,7 @@
  */
 
 	// Do you need a body for your reply posts?
-	$config['force_body'] = false;
+	$config['force_body'] = true;
 	// Do you need a body for new threads?
 	$config['force_body_op'] = true;
 	// Require an image for threads?