Merge branch 'feature_security_update' into 'master'

Classes/Command/SendMailCommandController.php

Classes/Controller/ConfigurationController.php

Classes/Controller/MailController.php

Classes/Controller/QueueController.php

Classes/Domain/Repository/AbstractRepository.php

Classes/Domain/Repository/MailRepository.php

Classes/Domain/Repository/TemplateRepository.php

Classes/Finisher/Forms/FormsFinisher.php

Classes/Service/BackendService.php

Classes/Service/MailTemplateService.php

Classes/Service/RegisterService.php

Classes/UserFunc/ExtensionConfiguration.php

Classes/XClass/Form/FormEditorController.php

Configuration/Yaml/Forms/FinisherSetupBE.yaml

README.md

Resources/Private/Language/de.locallang.xlf

Resources/Private/Language/locallang.xlf

Resources/Private/Templates/Mail/Index.html

ext_conf_template.txt

ext_localconf.php