Avoid clobbering of ROOT dictionaries.
Merge pull request #55 from adavidzh/linkdef_fix

Avoid clobbering of ROOT dictionaries.
Update new Pdf for HWW analysis
Update new Pdf for HWW analysis
Update new Pdf for HWW analysis
Merge pull request #57 from rgerosa/master

Implementation of new Pdfs for HWW-related EXO analysis
Changes to implement groups of nuisances #32
Part 1 - python code
Multiple group definitions are now merged as the union.
small fixes
Merge remote-tracking branch 'origin/groups_of_nuisances' into groups_of_nuisances