Revise Metadata
The current metadata is OK but it's not great for autogenerating code, as the ``name`` field can contain a lot of unusual characters that many programming languages will choke on. Additionally, we should introduce a tags array to allow for better categorical search.

The proposal is as follows:

- [x] Create a new ``code-name`` field that is only composed of known "safe" characters
- [x] Create a ``tags`` field that is an array of tags the glyph fits with