* Complete PHPStan Level 6
Fix https://github.com/FreshRSS/FreshRSS/issues/4112
And initiate PHPStan Level 7
* PHPStan Level 6 for tests
* Use phpstan/phpstan-phpunit
* Update to PHPStan version 1.10
* Fix mixed bug
* Fix mixed return bug
* Fix paginator bug
* Fix FreshRSS_UserConfiguration
* A couple more Minz_Configuration bug fixes
* A few trivial PHPStan Level 7 fixes
* A few more simple PHPStan Level 7
* More files passing PHPStan Level 7
Add interface to replace removed class from https://github.com/FreshRSS/FreshRSS/pull/5251
* A few more PHPStan Level 7 preparations
* A few last details
* PDO refactor
* Automatic prefix when using the syntax `_tableName`
* Uniformity: MySQL is now PDO::ATTR_EMULATE_PREPARES = false just like SQLite and PostgreSQL, with consequences such as only one statement per query
* Use PDO methods exec(), query(), prepare() + execute() in a more efficient way
* Remove auto-update SQL code for versions older than FreshRSS 1.5 (3 years old)
* The name of the default category is set in PHP instead of in the DB (simplies SQL and allows changing the name according to the FreshRSS language)
* Rename `->bd` to `->pdo` (less of a frenshism, and more informative)
* Fix some requests, which were not compatible with MySQL prepared statements
* Whitespace
* Fix syntax for PostgreSQL sequences
+ MySQL install
* Minor formatting
* Fix lastInsertId for PostgreSQL
* Use PHP 5.6+ const
Take advantage of https://github.com/FreshRSS/FreshRSS/pull/2527https://www.php.net/manual/en/migration56.new-features.php
* A bit of forgotten PHP 5.6 simplification for cURL
* Forgotten $s
* Mini fix custom user config
https://github.com/FreshRSS/FreshRSS/pull/2490/files#r326290346
* More work on install.php but not finished
* install.php working
* More cleaning of PDO in install
* Even more simplification
Take advantage of PDO->exec() to run multiple statements
* Disallow changing the name of the default category
https://github.com/FreshRSS/FreshRSS/pull/2522#discussion_r326967724
