++++++++++++++++++
* migrate to `RecurringUserPlan.renewal_triggered_by`
* add `renewal_triggered_by` parameter to `Payment.set_renew_token`
* deprecate `automatic_renewal` parameter of `Payment.set_renew_token`; use `renewal_triggered_by` parameter instead
* deprecate `None` value of `renewal_triggered_by` parameter of `Payment.set_renew_token`; set an `AbstractRecurringUserPlan.RENEWAL_TRIGGERED_BY` instead