Fix normalization issue with Molden files from latest PSI4.

[tovrstra]

Comment in code explains why this is needed:

# Files written by Molden don't need this and have properly normalized contractions.
# When Molden reads files in the Molden format, it does renormalize the contractions
# and other programs than Molden may generate Molden files with unnormalized
# contractions. Note: this renormalization is only a last resort in HORTON. If we
# would do it up-front, like Molden, we would not be able to fix errors in files from
# ORCA and older PSI-4 versions.

This change is needed to read Molden files from recent PSI4 versions (and maybe also other codes.)

[tovrstra]

Ready for review.