Commerce 2 Paybear.io gateway plugin (supporting subscriptions)

We need a Commerce 2 plugin for the Paybear.io (crypto currency) gateway developed. 

This plugin would need to support both one off payments for digital products and subscriptions.

For active subscriptions, we would request the payment a few days before renewal, and cancel the subscription if this is not made in time.

A Paybear plugin already exists for Commerce 1, https://github.com/ethercreative/commerce-paybear. Obviously this would need to be updated to work with Commerce 2 and have subcriptions support added.

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If you have an alternative suggestion for accepting crypto currency (bitcoin, etherium & litecoin) payments for subscriptions, we'd be open to this.