Happy New Disallowed Calls! (& some new config items and aliases)

• Optional root dir config/prefix (allowInRootDir) for all allowIn paths, needed when running PHPStan from a subdir for example (#102)
• Added disallow* aliases to allowExcept* config directives, might be more readable (#104)
• Can specify errorIdentifier in the config, will be more useful in the future, see phpstan/phpstan-src#844 (#97, thanks @ruudk)

Bugfix:

• Check allowedIn trait files, if the call is in a trait (#103)

Internal changes mostly:

• Works with composer 2.2.0 which requires plugin activation (#96, thanks @ruudk)
• Running tests on PHP 8.1 too (#98)
• When running tests manually & separately (not as part of composer test), the -dev suffix has been dropped. I'm probably the only one but you too can run only e.g. composer phpunit when building (and breaking) things (#101)