Update hwmatch.F



This code is provided to use FxFx-Merging with Herwig6 inside CMSSW.

Josh Bendavid created the first version of this code, which was loosely based on the old FxFx-Merging algorithm of the aMC@NLO authors and specially adopted to Higgs processes.
This adaption caused problems when used with other processes like ttbar. For that reason I ported it back to a newer version of the algorithm, see also http://amcatnlo.web.cern.ch/amcatnlo/mcatnlo_hwan_MLM.f
The same commit is also made in CMSSW 7_1_X
Merge pull request #4419 from mharrend/patch-1

Update hwmatch.F