history: Split multi-issuers and multi-recipients transfer into distincs rows

Reported on Duniter forum. multi-issuers (multi-sig) and multi-recipients transfers are merged together into one cell, because that’s how they are processed and stored into the blockchain. Specially with CSV output, it gets more convenient to treat each transfer placed into a dedicated cell. They would share the same date and reference.

• Split received and sent transfer containing multi-sig and multi-recipients into separated cells.

Adding (1/5) at the end of the transfer reference could help understand that they are stored into the same transfer. But would confuse regarding the real transfer reference. Does this information is interesting to the user? Let’s say no, and v1 support is getting closer to the end.