YITH Stripe Connect for WooCommerce Premium 2.31.0

* New French translation (thanks to Josselyn Jayant)
* Fix: Commissions with notes above 320 characters are not saved
* Fix: Prevent fatal error on unserialize function

* New: YITH WooCommerce Multi Vendor (3.0.0 +) support (admin can now pay vendors' commissions using Stripe Connect)
* Dev: added yith_wcsc_payment_complete action to add charge_id in stripe transfers

New: WooCommerce 3.4 compatibility
New: WordPress 4.9.6 compatibility
New: GDPR compliance
New: Spanish language
New: Italian language
New: Dutch language
New: added option to show Name on Card field at checkout
Tweak: now gateway works on pay page too
Tweak: added transfer group to charges
Update: plugin framework to latest revision
Dev: added filter 'yith_wcsc_schedule_timestamp_change_format'
Dev: added filter 'yith_wc_stripe_connect_credit_cards_logos'
Dev: added filter 'yith_wcsc_connect_account_template_args' to let third party code filter the connect template args
Dev: added filter 'yith_wcsc_account_page_script_data' to let third party code filter data in localize scripts for disconnection
Dev: added filter 'yith_wcsc_order_button_text'