Introduced DEBUG in GetLLM

This flag is used to decide if getbetax_dpp_'+str(k+1)+'.out and
getbetay_dpp_'+str(k+1)+'.out will be created or not.
Commented out getoct4000.out in GetLLM and GetLLM.valid


scriptrunner prints errors to stderr now.
Refactored getdiff.py and created testcase for it

For concrete changes see change history in module docstring of
getdiff.py.
Empty tfs files will not be created any more