wfdb.io.MultiRecord.wrsamp missing option for expanded=True

wfdb.io.MultiRecord.wrsamp (which just calls 'self.wrheader' and then 'for seg in self.segments: seg.wrsamp') seems to be missing the ability to pass 'expanded=True', as one can with wfdb.io.Record.wrsamp. 

This causes checksums to fail as the checks look for things related to 'd_signal' rather than 'e_d_signal', for example.