WP File Download - Joomunited 6.1.6

* Fix : Updater may not install correctly updates

* Fix : Category tree display issue on front-end
* Fix : Wrong multi categories of cloud file
* Fix : Missing link to Woo product description on single file
* Fix : PHP warning on admin

* Add : Pagination and load more options for file listing on admin
* Add : Possibility to add theme param to category shortcode
* Add : Possibility to order sub categories
* Add : Global settings for ordering direction for files and categories
* Fix : Import server files not work with uppercase file type
* Fix : Update date picker in the file search filter to avoid confusion
* Fix : Wrong pagination on frontend