Fix missing import

Just browsing code, pylint complained to me that in os.path.join() the os is not defined. I thought maybe it's imported implicitly by calling from modularAnalysis import *. But in the main modularAnalysis.py I only see lazy imports of os inside functions, no global import. I haven't actually tested whether the the join actually works without an explicit os import, so maybe you think it worked the way it was and should stay that way, then ignore this.