Digg Digg Short Codes

I have added shortcodes to Digg Digg with this commit.

Each short code will look something like the following: [dd_linkedin button="normal" url="http://example.com" title="Potential Custom Title"]

Each manual Digg Digg function now also allows a specific URL, and title to be passed to it to override the default behavior.

A scenario for this would be if you all likes and shares to go to the site's main URL. You could configure this to happen on all pages, except single posts.

I have tested this, but it has been a few weeks, and I need another set of eyes on it to look for any bugs.