WooCommerce Variation Swatches and Photos 3.1.11

* Update: Resolve warning in loading custom image sizes.
* Update: Fix compatibility warnings with WooCommerce 3.6

* Update: Do not overwrite default attribute selectors when in the admin, causes problems with adding variable items to manual orders.
* Update: Set default swatch configuration if none found for an attribute.
* Update: Allow sizes to be set on Taxonomy Images an Colors
* Update: Fix size lookup to include built in WP Sizes.

* Update: Added woocommerce_swatches_picker_default_label filter so users can add a default label.
* Update: Tested to WC 3.5.0