Add stream methods to the sampler API

default DoubleStream samples() {
    return DoubleStream.generate(this::sample).sequential();
}  

default DoubleStream samples(long streamSize) {
    return samples().limit(streamSize);
}  

UniformRandomProvider rng = ...;
double[] data = ContinuousUniformSampler.of(rng, 1.23, 4.56)
                                        .samples(50)
                                        .toArray();