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.