Three points are out of error-bounded while testing OptimalPLR with fb data

[lcgong]

While testing OptimalPLR with fb data, there are 3 points (166, 167, 168) out of error-bounded, gamma=64.

        let mut plr = OptimalPLR::new(64.0);
        let data = fb_data();

        let mut segments = Vec::new();

        for &(x, y) in data.iter() {
            if let Some(segment) = plr.process(x, y) {
                segments.push(segment);
            }
        }

        if let Some(segment) = plr.finish() {
            segments.push(segment);
        }

        verify_gamma(64.0, &data, &segments);

thread 'regression::optimal::test::test_optimal_fb' panicked at 'Prediction of 101.56824225187302 was not within gamma (64) of true value 166', src/test_util.rs:94:9

The intersection pint of red lines is the 166 data point (2979233417017651200, 166).