Herwig7_i support for showering LHE files generated from a UFO file containting BSM particle

Herwig7_i support for showering LHE files generated from a UFO file containting BSM particle

This merge requests adds a Python snippet that can be included in Herwig7 jobOption scripts.
Including the snippet allows users to have Herwig7 shower some input LHE file that
may contains BSM particle that are not recognised by the LHEReader otherwise.

Generators/Herwig7_i/share/common/Herwig7_UFO.py

+# Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
+
+# Python steering script for Herwig7_i to shower input LHE files
+# generated with a given UFO model
+#   written by Yoran Yeh <yoran.yeh@cern.ch>
+
+import os, shutil
+
+def generateFRModel(UFOModel, overWriteLocalDir=False):
+    """
+        UFOModel (string) :: name of UFO model that is imported for the event generation
+    """
+
+    # find UFO directory
+    MGModelsLatest = '/cvmfs/atlas.cern.ch/repo/sw/Generators/madgraph/models/latest/'
+    MGModelDirCVMFS = os.path.join(MGModelsLatest, UFOModel)
+    if not MGModelDirCVMFS:
+        athMsgLog.error('could not find UFO model ' + UFOModel + ' on cvmfs.' \
+                        ' Are you sure it is available on ' + MGModelsLatest + '?')
+        exit(1)
+
+    try:
+        shutil.copytree(MGModelDirCVMFS, UFOModel)
+    except OSError:
+        if not overWriteLocalDir:
+            athMsgLog.error(UFOModel + ' already exists in your local directory.' \
+                            ' Please (re)move this directory yourself to avoid it' \
+                            ' being overwritten, or set `overWriteLocalDir` to True.' \
+                            ' Exiting gracefully...')
+            exit(1)
+        else:
+            shutil.rmtree(UFOModel)
+            shutil.copytree(MGModelDirCVMFS, UFOModel)
+
+    # find ufo2herwig command
+    HERWIG7_PATH = os.environ['HERWIG7_PATH']
+    ufo2herwig   = os.path.join(HERWIG7_PATH, 'bin/ufo2herwig')
+    if not ufo2herwig: 
+        athMsgLog.error('could not find Herwig7 ufo2herwig command: ' + ufo2herwig)
+        exit(1)
+
+    # generate FRModel.model file
+    try:
+        os.system(ufo2herwig + ' ' + UFOModel)
+    
+    # it might be needed to convert python2 models to python3
+    except:
+    
+        # fresh copy of UFO model, as the previous attempt for `ufo2herwig` 
+        # will have made modifications in this directory
+        shutil.rmtree(UFOModel)
+        shutil.copytree(MGModelDirCVMFS, UFOModel)
+        os.system(ufo2herwig + ' --convert ' + UFOModel)
+
+    os.system('make')
+    
+    # add "read FRModel.model" to the Herwig7 command
+    Herwig7Config.add_commands("""
+read FRModel.model
+""")
+
+  
+