Provide a warning for unused actuators

[Myoldmopar]

General Summary

I debugged a file for quite a while due to weird behavior, only to have the error be a typo in an EMS program.

Detailed Description

There was an actuator named A1. Inside the program there was a SET Al = 2. But because of the typo, the Al variable was just a local variable that was never used. And the actuator was never assigned.

Possible Implementation

A simple flag on each actuator declared in the IDF to check if it was ever assigned seems sufficient. Then at the end of the simulation, a warning could be emitted for any never-assigned actuators.

As an aside, if this was done in Python, then the typo would have caused a failure when looking up the actuator handle, so this is moot there. It may not be worth adding this as we want to nudge people toward the Python side, but it would still be a light lift.