[DGD] Upgrade management

[Raymond Jennings]

Heck, why don't I ask about this on the list?  that's what it's for IIRC.

Presently, every time a program is compiled, the owning subsystem's initd
is asked for a "toucher" function.

Later, when a non inheritable is compiled that inherits that program, it
and all its clones are flagged with call_touch, which when triggered
invokes the toucher function in place before the object is manipulated.

Issues I'm trying to solve (and having SOME luck figuring out)

* enforcing serial upgrades so that data isn't lost by skipping a migration
* efficiency so that touchers aren't called redundantly.

But of coruse suggestions aren't limited to these issues.  Any thoughts?