Add a GeneratorVariableTracker class to manage un/tracked variables

[agarny]

Fixes issue #1339.

[agarny]

Note that I am not done yet...

[nickerso]

Why the change from GeneratorContext to GeneratorVariableTracker? Some useful commit messages would be great to start seeing. I am not a fan of that change and really struggling to see a need for this at all from the description of #1339...starting to sound more and more like some internal data management that needs no visible presence in the API.

[agarny]

Why the change from GeneratorContext to GeneratorVariableTracker? Some useful commit messages would be great to start seeing. I am not a fan of that change and really struggling to see a need for this at all from the description of #1339...starting to sound more and more like some internal data management that needs no visible presence in the API.

GeneratorContext is a bit too generic while GeneratorVariableTracker describes what the class is really about.

In the end, the idea is for the Generator class not to hold anything (i.e. a profile and a variable tracker are to be passed to interfaceCode() and implementationCode() rather than applied to a Generator object using setProfile() and setVariableTracker()).

Now, I agree that this is getting a bit out of hands and this is why I am finishing this cosmetic work (!!) now and this is it.

[hsorby]

I like this interface for the generator, I think it looks great.

[nickerso]

I don't think this is a good change, but happy to let it through. I assume documentation and tutorial updates are imminent that will help users transition our code to all these new APIs.