Update .mailmap file

Update .mailmap file

This commit updates email addresses of people, who are already in the
.mailmap file, so I'd assume they have sorted out their viewpoint on
privacy within the .mailmap file.

The entries for this commit have been produced using:
        # Finding out duplicates by comparing email addresses:
        git shortlog -sne |awk '{ print $NF }' |sort |uniq -d

        # Finding out duplicates by comparing names:
        git shortlog -sne |awk '{ NF--; $1=""; print }' |sort |uniq -d