WooCommerce Customer Order XML Export Suite 2.6.3

* Misc - Add the handler for migrating to the new unified Customer/Order/Coupon Export extension

* Misc - Add support for WooCommerce 3.8

* Fix - Fix issue preventing database-stored exports from displaying properly on some hosts

* Misc - Add support for WooCommerce 3.7
* Misc - Remove support for WooCommerce 2.6
* Misc - Require PHP 5.6+

* Fix - Fix an error which could occur when running certain third-party plugins
* Dev - Filter the maximum age of stored exports
* Misc - Add support for WooCommerce 3.6

* Feature - Add support for exporting coupons in default and custom formats
* Tweak - Remove debug option; always log messages

* Fix - Stop exports from aggressively clearing the WP object cache
* Misc - Add support for WooCommerce 3.5

* Fix - Fix an issue with malformed exports when using the filesystem data store

* Feature - Add new data store classes which allow for soring exports in the filesystem, database, or a custom data store
* Dev - Add `wc_customer_order_xml_export_suite_custom_data_store` filter to allow the use of custom data stores
* Dev - Add `wc_customer_order_xml_export_suite_auto_export_ids` and `wc_customer_order_xml_export_suite_auto_export_customers` filters to allow changing auto-exported ids
* Dev - Add `wc_customer_order_xml_export_suite_start_export_args` filter to allow changing the export arguments just before creation

* Tweak - Add option in control panel to enable or disable debug logging