Simple anti-spam mechanism

inc/config.php

@@ -303,7 +303,14 @@
 		'json_response',
 		'user_flag',
 		'no_country',
-		'tag'
+		'tag',
+		'simple_spam'
+	);
+
+	// Enable simple anti-spam measure.
+	$config['simple_spam'] = array (
+		'question' => 'What is 2 + 2?',
+		'answer' => '4'
 	);
 
 	// Enable reCaptcha to make spam even harder. Rarely necessary.
@@ -1158,6 +1165,7 @@
 	$config['error']['flood']		= _('Flood detected; Post discarded.');
 	$config['error']['too_many_threads']	= _('The hourly thread limit has been reached. Please post in an existing thread.');
 	$config['error']['spam']		= _('Your request looks automated; Post discarded.');
+	$config['error']['simple_spam']        = _('You must answer the question to make a new thread. See the last field.');
 	$config['error']['unoriginal']		= _('Unoriginal content!');
 	$config['error']['muted']		= _('Unoriginal content! You have been muted for %d seconds.');
 	$config['error']['youaremuted']		= _('You are muted! Expires in %d seconds.');