Bug: default implementation for computeLogAcceptanceProbability biases non-uniform sampling

Simple fix: 1->0

in

 double computeLogAcceptanceProbability() override {
            if(hasattr(pyObj, "log_acceptance_probability")) {
                return pyObj.attr("log_acceptance_probability")().cast<double>();
            }
            // default implementation: assumes the acceptance prob is 100%
            return 1;
        }