implemented support for config files, logging and progress bars.

So here comes support for ini-style config files, which is used for the logging config, implemented in ``lingpy.log``. The log level is then used in ``lingpy.util.ProgressBar``. I then replaced all uses of the former progress bar implementation with the new functionality. Unfortunately, being implemented as context manager (which I think makes a lot of sense), refactoring the code to use ``lingpy.util.ProgressBar`` caused a lot changes in indentation. Anyway, test suite still succeeds on py2.7 :)