0.21.0

What's Changed

• Replaced asserts by proper checks by @david-zwicker in #59
• Improved documentation by @david-zwicker in #60
• Updated and synchronized dependencies by @david-zwicker in #61
• Fixed tutorial notebook by @david-zwicker in #62
• Made h5py a required dependency by @david-zwicker in #63
• Improved get_length_scale by @david-zwicker in #64

Full Changelog: 0.20.0...0.20.1