Improved example of running real quality control checks

This is a partial attempt at improving the example of a real quality control check suggested in #24. The EN_range_check.py program is simplified and instead a driver routine AutoQC.py has been introduced that reads real data from files, runs the quality control check and prints results to screen. I haven't been able to attempt to implement the code for running checks developed in demo/demo.py into AutoQC.py. Should this be raised as a new issue now or should it be left until development of demo/demo.py is complete?