Add catch-all softlock protection

What this simply does is make it so that in the event that
game.hascontrol is somehow set to false when there isn't a cutscene
running (i.e. when game.state is 0 and script.running is false), it gets
set back to true again.

There's many ways to interrupt a gamestate and/or a running script, most
notably telejumping and doing a screen transition in the middle of the
animation, interrupting it.

This implements the first part of my idea in this comment:
https://github.com/TerryCavanagh/VVVVVV/issues/391#issuecomment-659757071

desktop_version/src/Game.cpp

@@ -649,6 +649,12 @@ void Game::updatestate()
         {
         case 0:
             //Do nothing here! Standard game state
+
+            //Prevent softlocks if there's no cutscene running right now
+            if (!script.running)
+            {
+                hascontrol = true;
+            }
             break;
         case 1:
             //Game initilisation