Bumping up version to v5.1 for release,
Add support for "Delete From Trash" addon,
Fix JavaScript validation for "Delete by URL" module,
Change the contextual help content for admin screens,
Add `EMPTY_TRASH_DAYS` to system info page,
Change instance variable to class name for accessing static members

git-svn-id: https://plugins.svn.wordpress.org/bulk-delete/trunk@932558 b8457f37-d9ea-0310-8a92-e5e31aec5664