update Pythia8 to v. 2.35 and interface to SVN tag 00-14-12 i.e. Update UserHooks/ZprimeFlatpT.cxx so that s-hat cuttoff can be set (default remains 3000 GeV) and an additional decay
10	        weight can be included below a settable s-hat (default 0.). The default behaviour is unchanged
Update UserHooks/WprimeWZFlat.cxx to add a new mode switched by WprimeWZFlat:FlattenPT to (duh) flatten the pT spectrum as well as the BW.
6	        The default is the old behaviour

update MG to v. 2.6.2.atlas2


Former-commit-id: dccb2eb90b918dd3bb7c06cf8314792635a77cc3