Approach is to have one SDL_Texture per doom and use SDL_RenderCopy() with
different destination rectangles to compose the layout. Apart from
SDL_UpdateTexture() and SDL_RenderCopy() no work is done per doom.
This scales up to ~200 doomsim instances. After that the frametime
increases rapidly and all my cores are maxed out.
TODO: test without spawning doomsim processes!
The internal unique id should not be needed, the pid is unique enough :)
Also this can allow starting dooms externally without having to pass an id
parameter that's not already in use. The externally started doom sends its
pid with the DoomReady message and the controller can add a new entry if it
needs to. Of course the controller will not be able to kill() these
externally started dooms.
When usleep()'ing in doomsim it misses most of the quit messages. I think
it's because the controller spams RunDoom all the time and the quit
messages get discarded while doomsim is sleeping.
