* system/msgdialog: callback available to be used by host
* sdl window: mouse capture var
* lib/pad: basic special pad impl scaffold & steering wheel
(config specialPadClass set to 6 is required)
* handle all mouse inputs & ask to capture when first opened
* added imgui as dependency
* imgui renderer/basic input implementation
* imgui: add layers system
Add video info layer to show fps. Press F10 to toggle it.
* imgui: add custom imgui config
* imgui: gamepad capture, stopping propagation
* imgui: changed config & log file path to use portable dir
* videoout: render blank frame when video output is closed
required to render imgui even when game has no video output
- fixed merge compile-error
