Fix prompt fade out when activating overlapping zones

If you stood in two activity zones at once, you'll automatically select
the one that got created first. And when you activated it, the activity
zone prompt would switch to fading out the prompt of the OTHER activity
zone, the one you didn't activate.

This wasn't a problem in 2.2 and previous, because the fading animation
was simply bugged and defaulted to being solid black. However, in 2.3,
the fading animation is fixed, so this is possible.

Also, this really only happens in the main game. Since there's only one
type of useful activity zone in custom levels - namely the terminal
activity zone - if two activity zones did happen to overlap, activating
one of them wouldn't result in visibly fading out a different activity
zone (because they both look the same); furthermore custom level makers
are careful to not overlap terminal activity zones, lest this result in
player confusion; furthermore the placed activity zones only cover a
small area, whereas in the main game, crewmates' activity zones are
pretty big.

(Technically, you CAN create main game activity zones in custom levels,
but those are hardcoded to call main game scripts, and basically nobody
uses them.)

So what's the solution? Simply adding game.hascontrol and script.running
checks to the updating of game.activity_last[prompt|r|g|b].

Why not add those checks to the assignment of game.activeactivity, just
above? Because that would introduce a frame ordering issue (that
would NOT be (automatically) fixed by #535) where the eligibility of
pressing Enter on an activity zone now checks if you were standing in an
activity zone LAST frame, and not THIS frame. (I tested this with
libTAS.) Better to fiddle with the rendering code than fiddle with the
actual physics code.

The specific spot I used to test this was standing in Violet's activity
zone and the activity zone of the ship radio terminals (the three
terminals on the ground in her room); the ship radio terminals are
first-placed, so if you're testing this (and you should!), make that the
prompt is of the ship radio activity zone before activation.

desktop_version/src/Logic.cpp

@@ -1527,7 +1527,8 @@ void gamelogic(void)
 
     game.activeactivity = obj.checkactivity();
 
-    if (INBOUNDS_VEC(game.activeactivity, obj.entities))
+    if (game.hascontrol && !script.running
+    && INBOUNDS_VEC(game.activeactivity, obj.entities))
     {
         game.activity_lastprompt = obj.blocks[game.activeactivity].prompt;
         game.activity_r = obj.blocks[game.activeactivity].r;