chore: remove demo code from project

src/main/java/ch/unibas/dmi/dbis/cs108/example/HelloWorld.java

@@ -1,12 +0,0 @@
-package ch.unibas.dmi.dbis.cs108.example;
-
-/**
- * A simple HelloWorld class.
- */
-public class HelloWorld {
-
-    public static void main(String[] args) {
-        System.out.println("Hello World");
-    }
-
-}

src/main/java/ch/unibas/dmi/dbis/cs108/example/gui/javafx/GUI.java

@@ -1,32 +0,0 @@
-package ch.unibas.dmi.dbis.cs108.example.gui.javafx;
-
-import javafx.application.Application;
-import javafx.scene.Scene;
-import javafx.scene.control.Label;
-import javafx.scene.layout.StackPane;
-import javafx.stage.Stage;
-
-/**
- * This is an example JavaFX-Application.
- */
-public class GUI extends Application {
-
-    /**
-     * Launching this method will not work on some platforms.
-     * What you should do is to create a separate main class and launch the GUI class from there as is done in {@link Main}
-     */
-    public static void main(String[] args) {
-        launch(args);
-    }
-
-    @Override
-    public void start(Stage stage) {
-        String javaVersion = System.getProperty("java.version");
-        String javafxVersion = System.getProperty("javafx.version");
-        Label l = new Label("Hello, JavaFX " + javafxVersion + ", running on Java " + javaVersion + ".");
-        Scene scene = new Scene(new StackPane(l), 640, 480);
-        stage.setScene(scene);
-        stage.show();
-    }
-
-}

src/main/java/ch/unibas/dmi/dbis/cs108/example/gui/javafx/Main.java

@@ -1,14 +0,0 @@
-package ch.unibas.dmi.dbis.cs108.example.gui.javafx;
-
-import javafx.application.Application;
-
-public class Main {
-
-    /**
-     * This is simply a wrapper to launch the {@link GUI} class.
-     * The reason this class exists is documented in {@link GUI#main(String[])}
-     */
-    public static void main(String[] args) {
-        Application.launch(GUI.class, args);
-    }
-}