Fix softlocks from turning off advancetext at wrong time

When a text box in the script system (not the gamestate system) is
displayed onscreen and "- Press ACTION to advance text -" is up, the
game sets pausescript to true, so the script system won't blare past the
text box and keep executing. Then it also sets advancetext to true.
Crucially, these two variables are different, so if you have pausescript
true but advancetext false, then what happens?

Well, you get softlocked. There's no way to continue the script.

How is this possible? Well, you can teleport to the (0,0) teleporter
(the teleporter in the very top-left of the map) and regain control
during the teleporter animation. To do that, in 2.2 and below, you have
to press R at the same time you press Enter on the teleporter, or in 2.3
you can simply press R during the cutscene. Then once you teleport to
the room, it's really precise and a bit difficult (especially if
Viridian is invisible), but you can quickly walk over to the terminal in
that room and press Enter on it.

Then what will happen is the terminal script will run, but the
teleporter gamestate sequence will finish and turn advancetext off in
the middle of it. And then you're softlocked.

To fix this, just add a check so if we're in gamestate 0 and there's a
script running, but we have pausescript on and advancetext off, just
turn pausescript off so the game automatically advances the script.

This softlock was reported by Tzann on the VVVVVV speedrunning Discord.

desktop_version/src/Game.cpp

@@ -735,9 +735,17 @@ void Game::updatestate(void)
         case 0:
             //Do nothing here! Standard game state
 
-            //Prevent softlocks if there's no cutscene running right now
+            if (script.running)
-            if (!script.running)
             {
+                if (pausescript && !advancetext)
+                {
+                    /* Prevent softlocks if we somehow don't have advancetext */
+                    pausescript = false;
+                }
+            }
+            else
+            {
+                /* Prevent softlocks if there's no cutscene running right now */
                 hascontrol = true;
                 completestop = false;
             }