New module selecting B->D0 Eta/Eta' decays

Apologies for the late submit triggered by recent discussions. This is a new module selecting 4 decay modes never studied by LHCb (some never observed) with photons in the final states. Cuts are tights and resulting rates should be small (The lines should go to full-DST.). Testing on 10k events, candidates are found to pass the combination cuts but not the mother cuts (see attachment b2d0x0_strip_1k.txt). Test with larger statistics are on-going. This request will be updated accordingly.