make refund to new address address in coin transfer of CLI opt-in

[GlenDC]

by default it should:

• refund to the address it funded from
• if multiple address choose the address with the highest funding participation

One can use the refund address flag to specify a different refund address as well as the refund-address-generate bool option flag to generate a new one if desired.

Currently it always generates a new address which is a bit overkill and it breaks users of the auth coin tx plugin.