feat: add timer for automatically falling pieces

src/main/java/eu/midnightdust/yaytris/Tetris.java

@@ -5,6 +5,8 @@ import eu.midnightdust.yaytris.ui.TetrisUI;
 
 import javax.swing.*;
 import java.util.Random;
+import java.util.Timer;
+import java.util.TimerTask;
 
 public class Tetris {
     public static final Random random = new Random();
@@ -19,5 +21,15 @@ public class Tetris {
         Settings.load();
         space = new Space();
         ui = new TetrisUI();
+        Timer timer = new Timer("Tetris falling pieces");
+        timer.scheduleAtFixedRate(new TimerTask() {
+            @Override
+            public void run() {
+                if (Tetris.space.getCurrentTetromino() != null) {
+                    Tetris.space.getCurrentTetromino().fall(1);
+                    Tetris.ui.getGamePanel().repaint();
+                }
+            }
+        }, 50, 1000);
     }
 }