Including a way to generate a json file like grid.json

We've got a bunch of internal docs that support our own work and as we're now using Material Design Icons we want to show them in our docs with the appropriate categories etc. There doesn't seem to be a way to do this within the repo at present.

In the fontIcon folder there is `MaterialIcons-Regular.ijmap` which just lists the name and codepoint. Ideally I'd to be able to generate something more like [https://design.google.com/icons/data/grid.json](https://design.google.com/icons/data/grid.json) with the gulpfile included with the repo.

I can see that being useful to many projects which include material icons. Presumably `grid.json` is maintained in some way like that?

Start by inspecting the gulpfile and fontIcon/MaterialIcons-Regular.ijmap to understand the repository's existing generation tasks and input data. Compare the requested output with the linked grid.json format; done means the repository can generate equivalent icon metadata for use by documentation and other projects.

Written by the indexing model from the issue text.