Code cleaning and localiziation enhancement

PlayWall/assets/de/tobias/playpad/assets/lang/_de.properties

...all/assets/de/tobias/playpad/assets/lang/ui_de.properties

.../de/tobias/playpad/assets/view/option/global/keysTab.fxml

PlayWall/src/application.yml

PlayWall/src/de/tobias/playpad/PlayPadMain.java

...obias/playpad/action/mapper/listener/KeyboardHandler.java

...ias/playpad/viewcontroller/main/MainViewControllerV2.java

...viewcontroller/option/project/PathsTabViewController.java

PlayWallCore/src/de/tobias/playpad/action/Mapping.java

...e/src/de/tobias/playpad/project/ProjectReferenceList.java