TensorFlow integration

[RenatoGeh]

We seek to integrate TensorFlow with the goal of implementing RAT-SPNs as proposed in [Peharz et al 2018]. However, as of yet, only Python is covered by the API stability guarantees, meaning it's the only language with the API to build models. Having said that, the Go API is still capable of training the model and running inference.

This means that if we were to add TF integration, we would have to add a Python layer for model creation. Once the model has been created, the user would then be able to export it to GoSPN for learning, running inference or whatever else GoSPN may offer.

This is obviously not ideal, but until Google provides a full API for C++, C or Go, this is the best we can do. Suggestions on how to deal with this are welcome.

References

[Peharz et al 2018] - https://arxiv.org/pdf/1806.01910.pdf