Data and MC production for D→hhɣ with ɣ→ee conversions (supersedes !1083)

Producing data tuples for D→hhɣ with hh=Kπ,KK,ππ and with photon conversions to e+e-. Electrons are reconstructed as either LL or DD. Several stripping-filtered MC samples are processed for signal and background studies. The MR supersedes !1083 (merged) (which was only for data tuples). The superseded tuples can be deleted after the new merge request is finalised.