Resolve "Comment deletion log links to an invalid comment"

Closes #4983 (closed)

• Purging a comment now requires a reason
• Purged comment actions are logged and the comment is moved to an archive for forensic purposes
• Visiting a comment permalink that has been purged now shows a purged page with the reason for deletion.
• Deleting a comment with replies will also delete and log all replies to the comment.
• Additional language entries added for purge actions
• Previously purged comment links are still broken.