Changes for imathics kernel

[poke1024]

I strongly suggest we merge the changes necessary to run Mathics as an imathics kernel into master. The current imathics branch is outdated and it's a pain to keep it updated. This is a proposal to add all necessary changes to master.

I've tested this with the experimental version in mathics/IMathics#11 under Jupyter 5.

[sn6uv]

Great idea

[poke1024]

Done.

Basically two changes:

(1) the callbacks in Evaluation are now gathered in a single class Output
(2) all image outputs (i.e. svgs, imgs) now output mglyphs

(2) has the advantage of working with Jupyter without additional JavaScript transformations. On the other hand, in order to not break any behaviours in the classic Mathics web frontend, I added JS code to convert mglyph to svg or img, so that there's really no change for the frontend JS logic.

I'm not sure about the max_allowed_packet size, which was changed in the imathics branch. Is it something that should always be unlimited for Jupyter kernels?

[sn6uv]

I was running into trouble with the max_allowed_packet_size when working with large images. I don't remember exactly what it was sorry.

[sn6uv]

This is breaking plots on Firefox for me:

Firefox left and Chromium right

[poke1024]

I cannot reproduce this using Firefox 48.0.1 under OS X; I added a svg.setAttribute('data-info', 'generated through convertMathGlyphs()'); in web/media/js/mathics.js:convertMathGlyphs() to make sure I really tested the code, but it ends up in my Firefox (see attached image) and it works. Which OS/Firefox versions are you using? Any extensions? JavaScript is enabled?

[sn6uv]

Cleared my cache and it seems to be fixed now. Not sure what the problem was, half of the SVG wasn't present in the HTML document.

[poke1024]

Maybe the new JavaScript didn't get loaded properly.