Add beamgas synrad background dataset

10000 events of merged backgrounds from beamgas and synchroton radiation for 10x100 ep energies and q2 10 to 100 keV

BACKGROUNDS/10x100/merged_lowstat/bgplussynrad_10x100_q2_10_100.csv

+BACKGROUNDS/10x100/merged_lowstat/bgmerged_10000_ep_noradcor_10x100_q2_10_100_run*,hepmc3.tree.root,0,0