Allow set CONNECT Request method

Update Guide contents

Update JSON constants references on PHPDocs

phpstan-ignore DateTime::createFromFormat fail

Update CODE_CODE_VERSION_NOT_SUPPORTED to CODE_HTTP_VERSION_NOT_SUPPO…

…RTED

Use Helpers library

Only parse Request body if Content-Type is application/x-www-form-url…

…encoded

Add Message::setHeaderName

Add HTTP Link entity-header on MessageInterface

Set mixed typehint for deprecated CSRF class constructor params