Partial adaptation to python3

Modify scripts to create options and decparser to work with both python2 and python3. Options files generated after modifications are identical to the ones before changes and Gauss was tested to run fine with one of the new options file. There are few quirks which we might want to remove in future when we do not have to support python2 anymore.

There are few other scripts which in the package which I did not look yet with some having to stay python2 in Sim09 versions as Gauss does not work with python3 there.