Passage of Golubria UI improvements

[Yermak]

• You can get the message "This passage doesn't lead anywhere!" in two cases:
  
  • You're trying to enter the only passage on the map.
  • All other passages on the map are blocked with monsters.
  It would be better if messages for these cases were different. By the way, message for the second case exists already in the code:
  

    Code:

  mpr("You enter the passage of Golubria.");
...
mpr("But it is blocked!");

  
  But it's inaccessible and never happens.
  
• If a passage you entered appears to be out of los after the jump, its image will stay on the map.
  Merfolk enters left passage:
  

  

  Golubria bug.png (49.41 KiB) Viewed 1378 times

  
  When you juggle several passages at a time it's very inconvenient to have these phatom images.
  Edit: Usually the white dot on the minimap is the player. But such out-of-los-jumps leave these white dots on the minimap.