Create proper ics_gen2Actor

This is superseding INSTRM-96.

We have an existing ics_gen2Actor which provides sequence numbers, accepts Gen2 commands for MHS actors, and provides the telescope and environment FITS cards. But all were implemented in ways too clumsy for PFS: subprocess.call("oneCmd.py ...") and a PFS-facing socket to provide sequence numbers and headers, basically.

The solution is to run both the g2cam and the actorcore main loops together, and to support enough cross-communications for our needs. I'm currently trying a couple of schemes but haven't settled on one yet.