got base level A* working -- super slowly
removed extraneous sorts and got runtime comparable to standard version
printing fringe size and positions handled
added heuristics but not yet really utilizing properly
using heuristics but have bugs
fixed heuristics to reflect goal location
fixed dropping of valid positions as result of changing g and f scores
changed name of file to stp-Astar0.rkt
combined g-score and f-score hashes to reduce memory load
improved combined g-f-score hashe and added abstract heuristic
IP: file-based Astar - also optional args in write-bs->file and read-bs->hcpos
added alternate vector-sort! etc.
added looping to a*-file-search but still needs to eliminate duplicates
a*-file-search removes duplicates and merges
README changes
merged astar and added fringefiles directory