- check if each pair in the trios is present in
both databases; if it's missing in one, the script
will exit.
- note however that if the ortholog peak DB is not present
but the Ks list database is complete, the distrbutions
will still be plotted, all without their modes. This was a
choice made some time ago that I didn't want to remove.

- Now if one or more species pair is missing,
the PDF will be generated and the available data
will be plotted.
- Checking for missing pairs is now done during
the main for loop and not before (outside) it.
- The missing pairs are listed at the end, after
the for loop.
- The missing pairs are listed as missing 1) from
both databases, 2) from only peak DB and 3) from
only Ks list DB.

- Every PDF page contains a trio with complete
data (Ks list and Ks peak estimate).
- If there are no complete trios for a PDF, the
file is not generated.
- More clearly logging when a species pair is
missing in DBs and the plotting of a trio is
skipped.