Add dummy hologram line used for generating empty space between lines

core/src/main/java/de/pxav/kelp/core/player/hologram/line/EmptyHologramLine.java

@@ -0,0 +1,14 @@
+package de.pxav.kelp.core.player.hologram.line;
+
+public class EmptyHologramLine implements HologramLine<Void> {
+
+  public static EmptyHologramLine create() {
+    return new EmptyHologramLine();
+  }
+
+  @Override
+  public Void display() {
+    return null;
+  }
+
+}