YITH Frontend Manager for WooCommerce Premium 1.37.0

* New: Integration with YITH WooCommerce Order Tracking Premium
* New: Search form for products section
* New: Filter order by status
* Update: Spanish language
* Fix: Show user information in Ship To column for guest users
* Fix: Replaced deprecated function get_woocommerce_term_meta() with get_term_meta()
* Fix: Replace the order ID with Order Number to fix issues with YITH WooCommerce Sequential Order Number
* Fix: Style issues with YITH Nielsen theme

* New: Support for WooCommerce 3.7
* New: Add Unpaid commissions amount in Dashboard for vendors
* Tweak: Add "woocommerce" body class in frontend manager dashboard page
* Fix: Some Style bugs
* Fix: Pagination style
* Fix: Vendor can't add product on admin area
* Fix: Wrong style in frontend manager page login page
* Fix: Placeholder disappears if an user remove the product featured image
* Fix: Placeholder disappears if an user remove all products gallery images

* Fix: Vendor can't add new products