added first version of ctbutterfly including a unit test
Python 3 fixes for ctool scripts
Integrate ctbutterfly tool.
Use new GCsv table constructor, set methods and save method.
Merge branch '1051-create-ctbutterfly' into integration

Conflicts:
	ChangeLog
	NEWS
Enable debug mode.
Put back "irf" for the calibration database.
Remove debugging.
Transform tab to spaces.
Correct test order (pipelines should be last).