WooCommerce Product Search 6.1.0

* Terms offered in taxonomy filters are now restricted to context on search results.
* Fixed usage of undefined variable to obtain heading_id in search filter.
* Improved how search is handled for search results pages with the Product Filter – Search, allows to narrow down results with the filter.
* Fixed uninitialized containers array in price filter.
* Fixed PHP_INT_MAX used for maximum price instead of empty maximum value in price filter, would display the odd PHP_INT_MAX when products without prices were displayed only.
* Guarded against fatal errors produced if the WC_Product_Data_Store_CPT class is missing due to messed up loading we cannot control.
* Added Jetpack synergy improvement to have our search engine take over product searches and let Jetpack still handle other search queries.
* Added the woocommerce_product_search_jetpack_search_should_handle_query filter that allows to modify our override.
* WooCommerce 3.8 compatibility tested based on current WooCommerce 3.8.0-beta.1

* Added an option to the live Product Search field that allows to sort results by SKU.
* Added the woocommerce_product_search_field_product_title filter.
* Added the woocommerce_product_search_field_product_description filter.
* Added the woocommerce_product_search_field_product_price_html filter.
* Added the woocommerce_product_search_field_product_add_to_cart_html filter.
* Fixed an issue with 404s obtained for filter requests directly on paginated results beyond the first page.
* Fixed an issue with no products obtained with paginated results beyond the first page with the [woocommerce_product_filter_products] shortcode.
* Fixed an issue where category or attribute filters rendered as dropdowns could end up disabled after applying a choice.
* Fixed potencial PHP notices on uninitialized widget instance attributes for the Product Search Field and Product Filter – Search widgets.

* Added the woocommerce_product_search_indexer_filter_content filter.