🔖 Faster indexation

What's Changed

• ⚡️ Better indexing performance by @policratus in #164

Full Changelog: v0.13.5...v0.14.0

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• Bump annoy to 0.17.1;
• Bump sphinx to 5.1.1;
• Minor documentation improvements and fixes;
• Adding more explanatory exception messages;
• Adding six more diverse feature extractors;
• Exposing feature extractor choices;
• Now characteristics can also be retrieved by its value;
• Changing numpy direct calls for tensorflow ones.