Set featureed image automaticly on save post/page

set-featured-image.php

<?php
/**
 * Plugin Name: Set featured image
 * Plugin URI:  http://wpengineer.com/2460/set-wordpress-featured-image-automatically/
 * Description: Set featureed image automaticly on save post/page
 * Version:     1.0.1
 * Author:      Frank Bültge
 * Author URI:  http://bueltge.de
 * License:     GPLv3
 */

// This file is not called by WordPress. We don't like that.
! defined( 'ABSPATH' ) and exit;

if ( ! function_exists( 'fb_set_featured_image' ) ) {
	
	add_action( 'save_post', 'fb_set_featured_image' );
	/**
	 * Set featured image on posts
	 * 
	 */
	function fb_set_featured_image() {
			
			if ( ! isset( $GLOBALS['post']->ID ) )
				return NULL;
				
			if ( has_post_thumbnail( get_the_ID() ) )
				return NULL;
			
			$args = array(
				'numberposts'    => 1,
				'order'          => 'ASC', // DESC for the last image
				'post_mime_type' => 'image',
				'post_parent'    => get_the_ID(),
				'post_status'    => NULL,
				'post_type'      => 'attachment'
			);
			
			$attached_image = get_children( $args );
			if ( $attached_image ) {
				foreach ( $attached_image as $attachment_id => $attachment )
					set_post_thumbnail( get_the_ID(), $attachment_id );
			}
			
	}
	
}

if ( ! function_exists( 'fb_add_thumb_column' ) ) {
	
	// posts columns
	add_filter( 'manage_posts_columns', 'fb_add_thumb_column' );
	add_action( 'manage_posts_custom_column', 'fb_add_thumb_value', 10, 2 );
	// pages columns
	add_filter( 'manage_pages_columns', 'fb_add_thumb_column' );
	add_action( 'manage_pages_custom_column', 'fb_add_thumb_value', 10, 2 );
	/**
	 * Add description for table head
	 * 
	 * @param   $cols  Array
	 * @return  $cols  Array
	 */
	function fb_add_thumb_column( $cols ) {
		
		$cols['thumbnail'] = __('Thumbnail');
		return $cols;
	}
	
	/**
	 * Add thumbnail, if exist
	 * 
	 * @param  $column_name  String
	 * @param  $post_id  Integer
	 */
	function fb_add_thumb_value( $column_name, $post_id ) {
			
		if ( 'thumbnail' !== $column_name )
			return;
		
		$width  = (int) 35;
		$height = (int) 35;
		
		$args = array(
			'numberposts'    => 1,
			'order'          => 'ASC', // DESC for the last image
			'post_mime_type' => 'image',
			'post_parent'    => get_the_ID(),
			'post_status'    => NULL,
			'post_type'      => 'attachment'
		);
		
		$attached_image = get_children( $args );
		
		if ( $attached_image ) {
			foreach ( $attached_image as $attachment_id => $attachment )
				echo wp_get_attachment_image( $attachment_id, array( $width, $height ), TRUE );
		} else {
			echo __( 'None' );
		}
		
	}

}

Sorry, but how implement this code?
Should I replace or include it in which lines of the original code?

@rpgmen: add this lines from my comment to the plugin, below all source, the init source and ready.

How to modify to support custom post type? for example I have custom post type 'property'

Bin ich nur zu blöd, dass ich den Download-Button nicht sehe? Wie kriege ich das Plugin sonst runter? Vielen Dank für eure Hilfe.

Maybe you public this plugin to WordPress repository?

@bueltge Strangely complement the script stopped working in the last version of WP ... the standard image that no longer appear when the post is saved ... could check the reason?

hello @bueltge I editliy my themes the component files individually. The markings on the slider component files: How do I bring small areas?http://prntscr.com/9bxbx4

so unhelpful and waste of time.