Enable shortcode to be passed a post_id

Just had to make this modification for a client and thought it’d be a good addition to the shortcode:

https://gist.github.com/nciske/8161571

It allows you to use [fb_button post_id=”45″] to allow the short code to be used on pages where the global $post variable is not set to the post being shared.

It also fixes the incorrect argument order — $content is always the second variable for a short code.
http://codex.ww.wp.xz.cn/Shortcode_API

http://ww.wp.xz.cn/plugins/facebook-button-plugin/