Got the filtering of expansions to work in astar.py.  Changed the astar_search to be a while
loop instead of recursive.  Added a print_bs() method to pot_solutions so that states can
print their board, moves so-far, and heuristic estimate all at once.
Removed most of the text printed for debugging.
Modified iddfs.py output to correspond (visually) to astar.py.  Tested both search
algorithms on a same puzzle with solution path length of 10; both found same length
solutions.