With56 body decays
add option for 5- and 6-body combinations (in ThOR). Use cases:
- Xi_bc+ -> J/psi D0 p+ K- pi+
- B_c+ -> J/psi pi+ pi+ pi+ pi- pi- (see LHCb-PAPER-2016-040)
potentially can think of 7- & 8- combinations as well, let's say B_c+ -> J/psi 7pi or Bs0 -> J/psi K+ K- 2(pi+ pi-).