wave.readtxt: Correctly set Psi4 data loaded from CoRe format
Before this change for CoRe-formatted text files, the Psi4 files were read but the strain data was set to the p4 attribute instead of the just-loaded Psi4 data.
Before this change for CoRe-formatted text files, the Psi4 files were read but the strain data was set to the p4 attribute instead of the just-loaded Psi4 data.