In particular, Iris updates its frame counter and timer in the outer method, so
if we only call the inner one, then its shadows and sky will not update
properly.
Since the render method also renders the GUI, we set the current screen to null
and cancel the HUD during rendering. MC also clears the depth before rendering
the HUD, which we don't want because it breaks the depth map export, so we
cancel that as well.
This also allows Vanilla post-processing (aka Super Secret Settings, aka Vanilla
Shaders) as well as entity outlines to function properly cause those are applied
in that method as well.
Should have done this a long time ago but better late than never.
Closes#321
3f2456ba65