Change the width of stream s of all currently loaded HMMs to n. Changing the width of stream involves changing the dimensions of all mean and variance vectors or covariance matrices. If n is greater than the current width of stream s, then mean vectors are extended with zeroes and variance vectors are extended with 1's. Covariance matrices are extended with zeroes everywhere except for the diagonal elements which are set to 1. This command preserves any tyings which may be in force.