WooCommerce Coupon Box 2.1.6

- Update: Minify some source code
- Update: Add Sendy email API

- Update: Add unsubscribe button to email template
- Update: Add setting for unsubscribe feature

- Update: Update Klaviyo api
- Update: Update Brevo (SendInBlue) api
- Update: Add customize option to edit image size for template 2,5,6
- Update: Add customize option to add and edit custom image
- Update: Add option to set coupon expire date and type

Update: VillaTheme_Support

Updated: Compatible with High-Performance order storage (COT)