Domenico Tiziani / ctools

Convert the cta_root2caldb.py script into a cscript and add unit test. The script only works if PyROOT is installed.

Instead of the cta_root2caldb.py script a generate_prod3_irf.py script was added to the example folder.

Add __version__ variable to ctools Python module.

Rename __init__.py file into __init__.py.in, add version number, and __init__.py creation instruction into configure.ac.