[FEATURE] Tags implementation

Classes/Controller/LatestController.php

Classes/Controller/ListByCategoryController.php

Classes/Controller/OverviewController.php

Classes/Controller/SingleViewController.php

Classes/Domain/Model/News.php

Classes/Domain/Model/Tag.php

Classes/Domain/Repository/NewsRepository.php

Classes/Domain/Repository/TagRepository.php

Classes/Service/GeneralService.php

Configuration/FlexForms/Latest.xml

Configuration/FlexForms/ListByCategory.xml

Configuration/FlexForms/Overview.xml

Configuration/TCA/Overrides/pages.php

Configuration/TypoScript/Common/setup.txt

Configuration/TypoScript/Frontend/constants.txt

Configuration/TypoScript/Frontend/setup.txt

Resources/Private/Language/de.locallang_backend.xlf

Resources/Private/Language/de.locallang_db.xlf

Resources/Private/Language/locallang_backend.xlf

Resources/Private/Language/locallang_db.xlf