Beta 0.3.0 (some API changes)

• Add benchmark framework
• Support panel datasets with global modelling
• Add minimal verbosity option to fit method
• Allow no metrics
• Repeat learning-rate range test 3 times, use log10 avg
• Update energy example notebook
• Require passing dataframe for validation data while training
• Update how to build documentation added to Contributing
• Documentation using sphinx (before: mkdocs)
• Now optional: using make_future_dataframe
• avoid double calls to normalization and fill missing data methods
• New notebook guiding how to collect predictions
• Make raw predictions available to user
• Embed Tutorials in documentation page
• Embed Docstrings in documentation page
• move data to ourownstory/neuralprophet-data repository
• New energy notebook on ERCOT data
• Support more types of custom loss functions
• remove reliance on attrdict, use dataclasses instead
• improved plotting legend
• fix issues