Beta release

Major update, a lot of code base rewritten.

Most important changes:

• revised syntax for model definition (esp. naming)
• scheduler-independent parallelization interface (currently supports native & ipyparallel)
• methods can now be run iteratively
• persistence to .npy files
• Bayesian optimization as a separate method
• sampling in BOLFI
• MCMC sampling using the No-U-Turn-Sampler (NUTS)
• Result object for BOLFI
• virtual vectorization of external operations

See the updated notebooks and documentation for examples and details.