bfhthesis: Female forms not considered in German for the terms author, advisor, co-advisor, expert, project partner, supervisor, co-supervisor

We got from our female students the feedback that they were not able to adjust the title page of the bfhthesis document class to use the correct German female form for author, advisor, co-advisor, expert, project partner, supervisor, co-supervisor. This issue is confirmed when looking at the corresponding translation file bfhtranslations-german.trsl. This is not an issue for English or French, as these languages make no distinction for these terms between male and female.