Added a pause menu

It was actually not that difficult surprisingly. Adding this was pretty
fun.

Scripts/BackToMenuLogic.cs

@@ -0,0 +1,13 @@
+using Godot;
+using System;
+
+public partial class BackToMenuLogic : Control {
+    public void _on_menu_button_up() {
+        Globals.IsPaused = false;
+        Globals.Score = 0;
+        Globals.ActiveEffect = "none";
+        Globals.EffectTimer = 0f;
+
+        BazookaManager.Write(BazookaManager.HighScore, Globals.HighScore.ToString());
+    }
+}