Sampling the configurations at finite temperature

[GiggleLiu]

Implement the sampling algorithm same as in
TensorBFS/TensorInference.jl#28

The goal is to draw samples $\sigma$ from distrbution
$$p(\sigma) \sim e^{-\beta E_\sigma}$$

[GiggleLiu]

One can port TensorInference for computing finite temperature properties with probabilistic inference techniques.

Please check this example for details.