A few plugin updates

Software

Admin menu plugin

• Now features links to go to the plugin and presentation screens
• No longer uses relative uri

External links

• No longer uses relative uri

Google analytics

• No longer uses relative uri

Opt-in front page

• No longer uses relative uri

Smart links

• No longer uses relative uri
• Now works in feeds

Static front page

• No longer uses relative uri

Sidebar tile

• No longer uses relative uri

Sidebar tile is pretty much obsolete, given the newly introduced widgets. But I'll be keeping it around nonetheless.