Drop current version of Seitosh code. The contents are taken vom branch master
of [Seitosh](https://git.scc.kit.edu/Seitosh/Seitosh). The current master
commit in Seitosh is 0cdd3c0568.

With this vendor drop libstfinv supports semicolons as an alternative to commas being used as field seperators in parameter values.

Commands executed in the root directory of IFOS2D:

    rm -rfv contrib/stfinv
    (cd ~/git/Seitosh/src/libs/libstfinv; tar cvf - $(git ls-files)) \
      | ( cd ~/git/IFOS2D/contrib; mkdir stfinv; cd stfinv; tar xvfps -)
    git add --force contrib/stfinv