Upstream changes
- Merge pull request 'Replace special feed and category numbers with constants.' (#104) from wn/tt-rss:feature/special-feed-and-cat-consts into master
- Change 'FEED_NOTHING' to 'FEED_DASHBOARD'.
- Merge pull request 'Bump PHPStan to 1.10.3, address some new warnings' (#103) from wn/tt-rss:feature/bump-phpstan into master
- Also use friendly names for special feed+cat IDs in the frontend.
- Replace special feed and category numbers with constants.
- Revert 7ed4fa4c1dbdd9df552cf6dd28907c6769911a0e and use @var instead.
- Remove unused 'Prefs::_delete()'.
- Address PHPStan warning about unused private method 'Prefs::_delete()'.
- Tweak to appease PHPStan in 'Pref_Feeds::_makefeedtree()'.
- Address PHPStan 'right side always true' in 'PluginHost::lookup_command()'.
- Address PHPStan 'right side always true' in FeedItem_RSS.
- Bump PHPStan from 1.8.2 to 1.10.3
- API: - sharedToPublished: add optional sanitize parameter (defaults to true) if disabled, allows inserting HTML into shared article content; - clean() already invokes strip_tags() so it's pointless to do both;