Extract type factory and registry from Type into TypeRegistry

Enabled the build against IBM DB2 on PHP 7.3 on Travis CI

fix #3479 (typos in example-code in QueryBuilder)

fix two typos in QueryBuilder, on of them reported in #3479

Fix the branch alias for master

Version was bumped to 2.10-dev in 27023276 but the branch alias was forgotten.

Update doctrine coding standard from 5.0 to 6.0

Updated PHPStan to v0.11.3

Use latest stable versions of sqlsrv and pdo_sqlsrv on CI

See https://github.com/Microsoft/msphpsql/issues/955

Remove more hard-coded mock classes

Avoid database connection from PHPUnit data providers

Make PHP 7.3 the primary PHP version on Travis CI

Replaced MockPlatform with the ones generated by PHPUnit

Fixed a typo in PoolingShardConnection phpdoc

Replaced Xdebug with PCOV for code coverage

Marked some test classes abstract

1. SchemaManagerFunctionalTestCase can be run only via an extending class. Otherwise, it skips all tests. If the test case is represented as an abstract class, PhpStorm will offer a choise of concrete classes which is very handy when debugging test failures.
2. DbalFunctionalTestCase and DbalPerformanceTestCase are meant to be used as base classes and don't contain any tests.

Replaced MySQL 5.7 installed from a PPA with an official Docker image

See https://travis-ci.org/doctrine/dbal/jobs/495144274 for the PPA issue.

CI: Test against PHP 7.4snapshot instead of nightly (8.0)

Fixed AppVeyor build configuration and the issue on SQL Server

PowerShell doesn't automatically handle exit codes of the invoked commands automatically, and $ErrorActionPreference = "Stop" doesn't seem working. Additionally, the ocular command is moved out of the "test_script" section to "after_test" since it's not part of the actual test.

PHPStan Level 7

Upgraded PHPUnit to 8.0