Threading with SDL

[Adrian Preuß]

I think I have found the problem: SDL2 for window creation.

Now I implemented my own window manager with contextual graphics 
bindings for Vulkan, OpenGL and DirectX (9/10/11/12) with a focus 
on threading and it seems that this is a good solution now.

Predefined libs/dubs like SDL2 or GLFW assume that the main 
handling exists on a static basis. I've spent hours trying to 
make it asynchronous, but it doesn't really work and only causes 
problems.