better random string generation and more tests (ecfp and splif)
better random string generation and more tests (ecfp and splif)

ktaneishi/deepchem,deepchem/deepchem,lilleswing/deepchem,ktaneishi/deepchem,miaecle/deepchem,peastman/deepchem,lilleswing/deepchem,miaecle/deepchem,deepchem/deepchem,Agent007/deepchem,peastman/deepchem,miaecle/deepchem,Agent007/deepchem,ktaneishi/deepchem,lilleswing/deepchem,Agent007/deepchem