When posting amounts or the running total contain more than one
commodity, register-csv now prints them comma-separated on one line,
instead of on multiple lines breaking the CSV output.
This is may not be ideal for CSV consumers; alternatives include
failing with an error, adding columns for additional commodities,
ignoring all but one commodity.
hledger-register-csv.hs now accepts the same -H, -A and -r flags that
register does (but not -w, which wouldn't make sense).
Note: remember, when running add-ons with the hledger executable, most
add-on command flags must be preceded by --. So it's:
$ hledger register-csv -- -H
