Progress: featureless make.

Progress: featureless make.

The return code 0 should not trigger an error (I forgot to explicitly return from the function).

Implement the environment variable handling.
Now that it is implemented, do not manage the custom environment variables via the "define" mapping.
Instead, let the environment variables be the data storage.
This now updates the environment variables and reads from the environment variables as requested.

The parameter values are supposed to load from the build settings if not defined.
When the build settings are loaded, then allow loading from the build settings.