do not reseed every event

See merge request atlas/athena!26770

Pythia8 Version Update, 21.6 branch (2019.09.23.)

See merge request atlas/athena!26750

This is to fix the issue discussed in
https://sft.its.cern.ch/jira/browse/SPI-1459.

remove unneeded package from Projects/AthGeneration/package_filters.txt

See merge request atlas/athena!26748

Another OpenLoops fix

See merge request atlas/athena!26743

Adding find_packages for OpenLoops

See merge request atlas/athena!26741

added find_package( OpenLoops )

See merge request atlas/athena!26714

Fix reweighting to only apply to Sampling>0 in LogicalExpressionFilter

See merge request atlas/athena!26694

update POWHEG bersion to ATLASOTF-00-04-01

See merge request atlas/athena!26685

update to Pythia8.43p3, EvtGen 1.7

See merge request atlas/athena!26613

patch from Giancarlo for Pythia8 default weight saved as first

count the number of produced LHE events

See merge request atlas/athena!26604

and print them as MetaData

Superchic Interface codes

See merge request !26305

Cleanup ART package: remove the software and only keep CMake

See merge request atlas/athena!26459

Fixed problem with initial random number seeds.

See merge request atlas/athena!25933

minevents handling

See merge request atlas/athena!26599

correct syntax in GenerateTruthJets, so that multiple jets filters could be used

See merge request atlas/athena!26568

add ART test with 2 jet filters

correct ART tests for LHE-only production to use Gen_tf.py

See merge request atlas/athena!26560

update to atlasexternals 1.0.56

See merge request atlas/athena!26547

Gen_tf to be run for both EVNT and TXT output production