ImGui is now initialized once at startup and shutdown before
terminating. graphics initialization is independent.
Move more imgui stuff into imgui drivers.
switch: set scaling on external screen to 1.4, same as xbox
UI scaling refactoring.
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