Add Thai, Polish, Swedish languages

What's Changed

• Add Thai language support by @wannaphong in #192
• Add Swedish stopwords by @RobertMartinis in #195
• Add Polish language support by @miso-belica in #226
• Add timeout to 'from_url' by @damienbose in #186
• Replace docopt with docopt-ng by @sudoskys in #191
• Fixed bug with LexRank's power iteration by @AryazE in #194
• Fixed ItemsCount to raise ValueError by @AryazE in #203
• Allow to pass language with any-case letters by @miso-belica in #207
• Add new Python versions by @miso-belica in #212
• Migrate package metadata to pyproject.toml by @miso-belica in #227

Full Changelog: v0.11.0...v0.12.0