Create HIGG1D3 for Higgs->yy + eta_c->4pi
Creating a new derivation format HIGG1D3 for Higgs->yy + eta_c->4pi search. Borrowing the good stuff from HIGG1D1 about Higgs->yy and adding the facility class EtacTo4TracksVertex in BPhys for eta_c. The new format's python file lives in DerivationFrameworkHiggs.