added example 5.3_15

4.1_9-priority-queue.py.out

-Best-First Search (algoritmus A*)
+Best-First Search (algoritmus A*) - implementace pomoci prioritni fronty
 Veskere jednoduche cesty mezi mesty Arad a Bukurest serazene vzestupne podle ceny:
 (418, ['Bukurest', 'Pitesti', 'Rimnicu_Vilcea', 'Sibiu', 'Arad'])
 (450, ['Bukurest', 'Fagaras', 'Sibiu', 'Arad'])