Py3k fixes
Working on new version of GSR file.
Add customized version of prettytable
Change _run_all so that flows are produced in a temporary dir
Fix unittests
Use scripts to generate reference NC files.
Regerae GSR files
Regenerate SIGRES files.
Fix unit test
Create new directory to store reference output files.
Move mc files to abipy.data.refs
Working on lesson_base*.py
Make sphix doc system compatible with py3k
Move open_hook to dev_scripts because it's not compatible with py3k
Continue to fix unit tests