Move code out of definitions

[rocky]

This moves builtin-creation out of mathics.builtin and core.definitions and into a new module.

I thing this is the last step before we actually move builtin creation of the Definitions initialization and into some one-time code.

[mmatera]

LGTM

[TiagoCavalcante]

LGTM - I'm just wondering now why MakeBoxes has to contribute first

[rocky]

LGTM - I'm just wondering now why MakeBoxes has to contribute first

It is not now - it was changed to be that way recently. And I wondered too why MakeBoxes has to contribute first. @mmatera had one of his long explanations, given the current code in master and the involved process it follows, why this makes things work.

You can probably find that in a recent PR that about "fixing" Makeboxes.

I wonder, though, if there isn't a simpler organization and way to do things that does not require this kind of special logic. We have seen this kind of thing over and over.

But for now, I am struggling just to pull stuff out of mathics.builtin and then the Definitions object. And we've seen this kind of behavior too - we can't begin to do what we want because the logic of code is a bit involved, not well written or documented.

The wrongness of rereading module definitions over and over goes back to the earliest days V 0.5. But since then instead of addressing what I think is the root cause building definitions once, a complicated custom module cache code was added as a workaround. (Okay - caching allows the not-needed feature that you can run mathics, change a Python module, and possibly do something that will cause the module to reload and then see that new code.)

Then pymathics was added, and then this MakeBoxes fix was added (or is in the process of being added?)

Fixing the V 0.5 version is much easier than fixing the code as it is now. This is what happens when you build on a features on a foundation that isn't solid to begin with.

[mmatera]

It is because other symbols can add rules to the MakeBoxes definition. Hopefully, we are going to get ride it this behavior