Properties to Synth/Lockfile for CMD/isoc counts

These are properties count the number of CMDs and grouped
isochrones being managed by Synth, and are needed by SFH.
Add SFH class

SFH interfaces to StarFISH's `sfh` program. This initial draft
of SFH interfaces to the `Mask` and `Synth` classes to ultimately
run `sfh`.

Lockfile can produce a null hold file for SFH and can also produce
the `cmdfile` needed by `sfh.` Lockfile tracks active CMD groups,
and number of CMD planes via properties.