Marianne Lemoine / ctools

According to a study by Stephan Fegan done in the context of Fermi/LAT analysis, the best way to determine a butterfly diagram is to draw the envelope of the error ellipse of the model parameters. I implemented this method now in ctbutterfly. I also changed the output file, having now two columns giving as function of energy th minimum and maximum intensities.

Conflicts:
	examples/show_butterfly.py

Without the energy margin, roundoff errors may lead to the exclusion of the energy bin in case that a single energy bin is used.

…d in observation ebounds. Also added some improvements to csspec.

…no selection was performed)

Conflicts:
	scripts/csresmap.py

…lso modified consistently, csresmap can now also take two maps (cnt and model) as input and compute the residuals directly. The algorithm parameter has been made unhidden

…gning the old best optimizer result).