getFeatureArr now supports transformation of neighbourhood data; PredWvltSgmtn attempt to make use of this, but the matrix methods do not yet cooperate
put nystrom and pdeGraphSgmtn code in their own functions; Cleaned up PredImgSgmtn and PredUSHouseVoting; Wrote PredFourierSgmtn and PredWvltSgmtn; wrote arrExplore function and corresponding example; cleaned up getFeatureArr and added ability to return tranformed data (e.g., using abs(fft2(...)) )