Added some fake difficulty to the Dorim level.

The way it was previously, you always knew exactly where the WEAPCO
scientist was. I don't remember if this was the case in the original
game (I don't think it was), but regardless, this makes the mission
seem incredibly short and easy, and it ends up centering on the
secondary objective rather than the primary objective. Now, you have
to search through all the asteroids until you find the right one,
and you have to pay close attention to explosions. Collecting ore is
just something you do along the way.

It may be fake difficulty, but after all, tropes are not bad.

src/game.cpp

@@ -1512,9 +1512,6 @@ int mainGameLoop()
 		case MISN_URUSOR:
 			player_setTarget(ALIEN_SID);
 			break;
-		case MISN_DORIM:
-			player_setTarget(0);
-			break;
 		case MISN_EARTH:
 		case MISN_VENUS:
 			player_setTarget(ALIEN_KLINE);