PowhegControl: update of ttjMiNNLO AGENE-2055 and first implementation of 4tops process AGENE-2128

As the title suggests, this makes an update of the ttjMiNNLO process (now using public code from authors) and makes a first implementation of the interface to the 4tops process, in Powheg. Both would need to be tested using export POWHEGPATH=/afs/cern.ch/atlas/offline/external/powhegbox/ATLASOTF-05-02. More details are given in the ticket.

Generators/PowhegControl/python/parameters/registry.py

@@ -108,6 +108,7 @@ class Registry(object):
         self.add_default("dec3", -1, hidden=True, description="Weakino decay 3. UNUSED")
         self.add_default("dec4", -1, hidden=True, description="Weakino decay 4. UNUSED")
         self.add_default("decaymode", 0, description="Dark matter decay mode")
+        self.add_default("decay_signature", "0", description="4tops decay signature")
         self.add_default("delg1_g", 0, description="Delta_g1(Gamma)")
         self.add_default("delg1_z", 0, description="Delta_g1(Z)")
         self.add_default("delk_g", 0, description="Delta_K(Gamma)")