WooCommerce Smart Coupons 9.18.0

* Fix: Warning: call_user_func() expects parameter 1 to be a valid callback, class 'SA_WC_Compatibility_4_4' does not have a method 'get_smart_coupons_version'
* Update: POT file

* New: Tested up to WooCommerce 5.7.1 & WordPress 5.8.1
* Update: Use transient for auto-cleanup of options that starts with 'sc_applied_coupon_profile_'
* Update: Spellchecks
* Update: POT file

* New: Settings in acknowledgement email ('Subject' and 'Heading') to handle texts related to scheduled email
* New: Option 'wc_sc_auto_apply_coupon_removable' and hook 'wc_sc_is_auto_apply_coupon_removable' to allow removal of auto-apply coupons
* Fix: Under 'Import Coupons' 'Email coupon to recipients?' not appearing if there is no email added in the first row of the CSV file
* Fix: Incorrect calculation in store credit when used in manually created orders
* Fix: Coupon type in the acknowledgement email is always of the discount type 'smart_coupon' irrespective of the coupon sent
* Developer: New hook 'wc_sc_redirect_url_after_smart_coupons_process' to allow 3rd party plugin to modify the redirect URL after the plugin has processed the URL coupons
* Update: Tweaking in auto-apply feature
* Update: Changes in texts in email templates for acknowledgement email
* Update: Allow removal of auto apply coupons
* Update: Spellcheck for 'Coupons', 'arguments'
* Update: POT file