Restructure plugin files and folders. Uses a standardized class for the main plugin setup.
Included the actual taxonomies.php file.
Clean up undefined index error.
Overhaul template tags.  Most of them aren't needed anymore.
`echo` argument should be `true` by default.
Better method of getting the current post ID for the related series list.
Make sure we have a post ID.
Overhual widgets.
Rename widget files.
Remove unused admin() method.
Update translation files.