E3S9: Ensure the map is updated during a white screen transition

Without this [redraw] step, the wall dividing Engineer Fendyrn's spawn
and the rest of the boss chamber is visible for a split second after the
white screen flash.
E3S9: Warp to Engineer Fendyrn's spawn first on 1.11.0+

Scroll immediately to the target location if we have the warp-scroll
feature (1.11.0 and later). We don't want to try to do that before
restoring the screen state on 1.10.x because scrolling could take any
amount of time depending on the user's preferences, and that could ruin
the intended WHITE_SCREEN flash effect.
E3S9: Minor prose tweaks
Version 0.9.9