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.
libretro: Null first frame erroneously set as valid causing a crash with dx11 (single-threaded rendering)
libretro: pass dx11 compiler pointer to shaders
dx11: use feature level to check if per-pixel is supported
dx11: use 32-bit float depth texture to avoid loss of precision (SA2 into logo)
dx11: cache shader blobs to disk if not provided by OS
dx11: swap interval depends on screen refresh rate (1 for 60 Hz, 2 for 120 Hz, ...)
dx9: use clipping planes to avoid interpolation errors in rasterizer (daytona, mermaid lake)
directsound: use comptr
gui: fix navigation issue with OptionArrowButtons due to missing id
dx11: support for vmu and lightgun crosshair overlays
dx11: implement inside clipping (fixes 18 wheeler rear view mirror)
dx11: tentative 4K support on xbox
iOS,uwp: save log file in home (iOS)/data(uwp) directory
uwp: don't sign app on pull requests