A solution to two tokens setup for Neutrino Protocol: alternative mechanics

For context see Two token setup for Neutrino Protocol (by a neutrino community task force)

An alternative implementation of that proposal could be: once bonds are issued, they decay at a constant rate. And as long as they exist, each one share the same weight and powers as one NSBT.

This alternative replaces 3, 4a, 4b and 6 of original proposal. Everything else is similar.