Rename GUI.Hud.ToPixel() in GUI.ToPixel(), add camera argument to GUI.ToSceneUnit() and GUI.ToPixel(), rename GUI.Hud.FixPosition() in Vector2.EnsureNumberPixel().
GUI.Hud.RegisterCamera() now sets the hudOriginGO reference on the camera game object instead of the camera component.
Remove GUI.Awake(), remove reference to GUI.pixelsToUnits + stuffs.
Update calls to GUI.ToSceneUnit() with camera argument.
Update GUI.Hud scripted behavior.
Update scripted behaviors for GUI.Input, Slider and TextArea.