added periodic option to ContactFeaturizer
added periodic option to ContactFeaturizer

Eigenstate/msmbuilder,msmbuilder/msmbuilder,msmbuilder/msmbuilder,Eigenstate/msmbuilder,Eigenstate/msmbuilder,msmbuilder/msmbuilder,Eigenstate/msmbuilder,Eigenstate/msmbuilder,msmbuilder/msmbuilder,msmbuilder/msmbuilder