When rendering happens after the render timeout (initial sega copyright
screen and more), the frame is never swapped and never displayed. Causes
a crash in vk since the acquired swapchain image is never
presented/released.
Refactor imgui backend code into imgui drivers for gl, vk, dx9
Generic GraphicsContext interface for gl/vk/dx9 contexts
Simplify graphics api switching code
dx9, gl(sdl): set swap interval based on monitor refresh rate.
Flyinghead