Merge with development

public/img/Firefox.png

public/img/Firefox_Standard.png

resources/assets/less/metager/general.less

resources/assets/less/metager/modals.less

resources/assets/less/metager/specific.less

resources/assets/less/metager/start-page.less

resources/assets/less/metager/variables.less

resources/lang/de/index.php

resources/lang/de/plugin-page.php

resources/lang/de/sidebar.php

resources/lang/de/titles.php

resources/lang/en/index.php

resources/lang/es/index.php

resources/views/datenschutz/english.blade.php

resources/views/datenschutz/german.blade.php

resources/views/impressum.blade.php

resources/views/index.blade.php

resources/views/modals/plugin-modal.blade.php

resources/views/parts/sidebar.blade.php

resources/views/plugin-page.blade.php