Ala

added String with heuristics of each state

new usage:
String solve -> void solve //to start engine
String getHeursiticsArray()  //to get Heuristics of all states; it start from goal position to start position
String getStates()  //to get String with all states

All function throws exception. If it was handled in engine there would be 3 blocks of try-catch with only one instruction. It's not the best solution to relocate it to GU, so we need to find better one.