Loading screen

[SimplyLiz]

On windows, it takes ages for the game to start, because the Audio assets are loaded really slow.

Add a loading screen to show that the game is not stuck. I found this example. https://glusoft.com/tutorials/sdl2/loading-screen

[lizzyd710]

This is kind of related, but I noticed that the buttons don't highlight when hovered over until the logo finishes fading in. You can still click on them, but without sound, you wouldn't know it did anything or detected UI events yet. It's super minor but could cause confusion. I was thinking possibly having the logo fade in on a separate thread?