Work in Progress for running custom wp_ajax actions

custom-ajax.php

<?php

/*--------------------------------------------------------------------------

	Better AJAX for WordPress

	inspired by:
	http:wordpress.stackexchange.com/questions/28342/is-there-a-way-to-use-the-wordpress-users-but-without-loading-the-entire-wordpre#answer-45011

--------------------------------------------------------------------------*/

//mimic the actuall admin-ajax
define('DOING_AJAX', true);

if(!isset($_POST['action'])) {
	die('1');
} else {
	ini_set('html_errors', 0);
	define('SHORTINIT', true);

	//Typical headers
	header('Content-Type: text/html');
	//Disable caching
	header('Cache-Control: no-cache');
	header('Pragma: no-cache');

	require_once(dirname(dirname(dirname(dirname(__FILE__)))) . '/wp-load.php');

	// Load most of WordPress.
	require_once( ABSPATH . WPINC .'/plugin.php');
	require_once(ABSPATH . WPINC . '/l10n.php');
	require_once( ABSPATH . WPINC . '/class-wp-walker.php' );
	require_once( ABSPATH . WPINC . '/formatting.php' );
	require_once( ABSPATH . WPINC . '/capabilities.php' );
	require_once( ABSPATH . WPINC . '/query.php' );
	require_once( ABSPATH . WPINC . '/theme.php' );
	require_once( ABSPATH . WPINC . '/user.php' );
	require_once( ABSPATH . WPINC . '/meta.php' );
	require_once( ABSPATH . WPINC . '/general-template.php' );
	require_once( ABSPATH . WPINC . '/link-template.php' );
	require_once( ABSPATH . WPINC . '/post.php' );
	require_once( ABSPATH . WPINC . '/comment.php' );
	require_once( ABSPATH . WPINC . '/rewrite.php' );
	require_once( ABSPATH . WPINC . '/kses.php' );
	require_once( ABSPATH . WPINC . '/cron.php' );
	require_once( ABSPATH . WPINC . '/script-loader.php' );
	require_once( ABSPATH . WPINC . '/taxonomy.php' );
	require_once( ABSPATH . WPINC . '/shortcodes.php' );
	require_once( ABSPATH . WPINC . '/media.php' );
	require_once( ABSPATH . WPINC . '/http.php' );
	require_once( ABSPATH . WPINC . '/class-http.php' );
	require_once( ABSPATH . WPINC . '/widgets.php' );
	require_once( ABSPATH . WPINC . '/nav-menu.php' );

	wp_plugin_directory_constants();
	
	foreach ( wp_get_active_and_valid_plugins() as $plugin ) {
		include_once( $plugin );
	}
	unset( $plugin );

	//call action and exit
	$action = trim($_POST['action']);

	do_action('ia_custom_ajax_nopriv_' . $action);

	die('0');
}