Loads the footer info.

• Sets up the appropriate info for the "Page loaded in x seconds with y queries" message
• Loads the "{layer}_below" sub-template for each layer in $context['theme_layers']
• Sets $context['theme_dir'], $context['images_url'] and $context['theme_url'] back to their "actual" values if $context['use_default_images'] is set to 'defaults'
• Outputs a warning message and logs an error if the copyright function was removed from the template
• Removing the hard-coded warning message is a violation of the license (so don't do it!)