* Make f_{block,unblock}_ptp_bvc_from_pcu handle multiple SGSNs
* gbproxy: Generalize as_count_bvc_block() into as_count_bvc_sts()
* NS_Emulation: Use endpoint list for SNS-CONFIG payload
* NS_Emulation: Use the "endpoint" mode of NS_Provider_IPL4
* NS_Provider_IPL4: Implement new "endpoint" mode