feat(jui): add world leaving

You will now be able to leave the world from all places where you'd usually be able to (Pause screen, death screen)
Should be identical to the way it's done on Iggy/XUI

Minecraft.Client/UI/Screens/DeathScreen.cpp

@@ -3,6 +3,7 @@
 #include "DeathScreen.h"
 #include "../Button.h"
 #include "../../Player/MultiPlayerLocalPlayer.h"
+#include "PauseScreen.h"
 #include "TitleScreen.h"
 
 void DeathScreen::init() {
@@ -30,9 +31,11 @@ void DeathScreen::buttonClicked(Button* button) {
         //          minecraft.setScreen(new NewLevelScreen(this));
     }
     if (button->id == 2) {
-        // TODO: proper world exits
         // minecraft->setLevel(NULL);
         // minecraft->setScreen(new TitleScreen());
+
+        // 4jcraft: use the static method from PauseScreen to exit
+        PauseScreen::exitWorld(minecraft, true);
     }
 }