optimised successors function for sudoku to use the most complete row, column or sub-square
Added helper functions for selecting next position to solve for sudoku
Heuristics for Sudoku updated and tested for A*, works but slow, 30 seconds

Create A* search algorithm and added to search algorithms.

Heuristics file with maze heuristics.

Moved puzzle goal to the top

Created test case for mazes

Create A* search algorithm and added to search algorithms.

Heuristics file with maze heuristics.

Moved puzzle goal to the top

Created test case for mazes