Change interface for accessing model parameters
Rename Visible to Conditional
Cleanup of Conditional
Rename BernoulliVector to BernoulliVectorConditional
Refactor Latent into Prior and Posterior
Adapt VAE to the new prior/conditional/posterior interface and factor out KL computing
Adapt YAML example script and fix bugs encountered in the process
Add automatic KLIntegrator finding
Adapt unit tests to new interface and fix encountered bugs