Neaten up mcsActor db access

The mcsActor reads and writes a number of opdb tables, These have been added over time and from different sources, and so use several mechanisms for db access. To pick three, direct pysopg2/spt_operational_database, pandas.to_sql, and COPY-based bulk transfers.

That last one in particular does not work with the reprocessing scheme we have implemented, so needs to be wrapped. And a few other things need to be cleaned up to support reprocessing.