A plugin, which allows editing certain template regions [duplicate]

This is standard WP functionality and can be accomplished without a plugin.

1. Using the admin area, create a page called Footer.

2. in you theme’s footer.php file, add the following code inside the main footer <div>.

   <?php
   $query  = new WP_Query(array('pagename'=>'footer'));
   while ( $query->have_posts()) : $query->the_post();
     the_content();
   endwhile;
   ?>
   

3. Now any text in the footer ‘page’ will appear there in your theme.

It would be possible to make the interface clearer with a custom post type, but this is the simplest way to do it.