tinyboard post.php json support

### inc/functions.php:

// the user is not currently logged in as a moderator
$mod = false;

+// Setting to true will cause error messages to be given as JSON.
+$wantjson = false;
+
register_shutdown_function('fatal_error_handler');

...

function displayBan($ban) {
-	global $config;
+	global $config, $wantjson;

	$ban['ip'] = $_SERVER['REMOTE_ADDR'];

	$banhtml = Element('page.html', array(
			'title' => 'Banned!',
			'config' => $config,
			'body' => Element('banned.html', array(
				'config' => $config,
				'ban' => $ban
			))));

+	if ($wantjson) {
+		header('Content-Type: application/json');
+		die(json_encode(array('error' => 'ban', 'banhtml' => $banhtml)));
+	}
+
	die($banhtml);
}

### inc/display.php:

function error($message, $priority = true) {
-	global $board, $mod, $config;
+	global $board, $mod, $config, $wantjson;

	if ($config['syslog'] && $priority !== false) {

...

	if (defined('STDIN')) {
		// Running from CLI
		die('Error: ' . $message . "\n");
	}

+	if ($wantjson) {
+		header('Content-Type: application/json');
+		die(json_encode(array('error' => 'message', 'message' => _($message))));
+	}
+
	die(Element('page.html', array(

### post.php:

} elseif (isset($_POST['post'])) {

+	if (isset($_POST['wantjson']) && $_POST['wantjson'])
+		$wantjson = true;

	if (!isset($_POST['body'], $_POST['board']))
		error($config['error']['bot']);

...

	$root = $post['mod'] ? $config['root'] . $config['file_mod'] . '?/' : $config['root'];

-	if ($config['always_noko'] || $noko) {
+	if ($wantjson || $config['always_noko'] || $noko) {
		$redirect = $root . $board['dir'] . $config['dir']['res'] .

...

	rebuildThemes('post');

+	if ($wantjson) {
+		$response = array();
+		$response['status'] = 'success';
+		$response['postid'] = intval($id);
+		$response['threadid'] = $post['op'] ? null : intval($post['thread']);
+		$response['board'] = $board['uri'];
+		$response['url'] = $redirect;
+
+		header('Content-Type: application/json');
+		die(json_encode($response));
+	}

	header('Location: ' . $redirect, true, $config['redirect_http']);
} else {