v2.0.18: Alpha support for Catalan and dependency fixes

✨ New features and improvements

• NEW: Alpha tokenization support for Catalan.
• Improve French tokenization.
• Fix regex pin to harmonise dependencies with conda.
• Fix msgpack pin.
• Update tests for pytest 4.0.

🔴 Bug fixes

• Fix issue #2933: Correct mistake in is_ascii documentation.
• Fix issue #2976: Fix bug where Vocab.prune_vectors did not use batch_size.
• Fix issue #2986: Correctly document when Span.ents was added.
• Fix issue #2995, #2996: Fix msgpack pin.

📖 Documentation and examples

• Fix various typos and inconsistencies.

👥 Contributors

Thanks to @mpuig, @ALSchwalm, @bpben, @svlandeg and @wxv for the pull requests and contributions.