Representation and Expansion

Have a set of data-definitions for representing boards, tiles, moves, etc. and implemented
expand, that takes a board position and produces all positions reachable from the given position.
added goal checking and integrated fringe-search
filter dups in fringe-search
change position representation to hash of sets
converted fringes from lists to sets
Expanding Multi-steps per Piece

Implemented multi-step expansions for a single piece when that is possible given the position.
Testing against Climb12, the fringe sizes correspond to Glenn's CL code.  However, on Block10,
it does not reach goal and runs into dead-ends (in-progress).
copied stp-solve-start in prep for cluster split
split code for common and cluster/single-specific
added cluster file
debugging Racket version
debug Block10 missing moves problem
Initial Cluster Version

the stp-solve-cluster.rkt code is currently 'functional' but still slower than doing it on one node.
minor tweaks trying to balance compute/network load
added a racket file writing example
added the riottest folder for examples
renamed and recursivized my-vec-member?/vec-member?
Profiling and Data Definitions

Tried (and failed) with profiling the code.

Started the overhaul of stp-solve-base that will involve a new and more compact representation of positions.
This will eliminate sets and hashes from the position representation but they may (or not) be used in other
contexts.
(Experimental) write-to-disk functionality is now implemented in 'expand-fringe'

Needs to be tested more.

Still needs to have duplicates removed when the new-fringe is being written. I assume that this will be a simple task if the file writing is working correctly.
Made changes to how the fringe-search reads in files and allowed the port to be closed in expand-fringe.
New Position Representation

Eliminated the hash/set way of representing states in favor of a vector of lists.  Resulting
runtime is less than half of what it was.  Still have sets in the expand chain but this can be isolated
entirely within a compute process; i.e., data passing between processes need not have any sets.