This builds upon #30 and #33 by adding support for randomly nested symbols in complexity levels 0-4 of the creature page.
Currently, we don't _recursively_ nest symbols, so e.g. we won't make an eye containing an eye containing a cube. And for now we'll only add a nested symbol if the parent symbol has the `always_nest` metadata property defined.
This fixes#20 by adding support for TOML-based metadata for symbols.
There's now a template TOML file in `svg/_template.toml` that documents all the different metadata properties. The file can be copied to match the name of an SVG file (but with a `.toml` extension) and it will be processed by the vocabulary builder when the site is generated.
Currently there are only two properties documented, `always_nest` and `always_be_nested` (as per the needs outlined in https://github.com/toolness/mystic-symbolic/issues/17#issuecomment-786696966), but they don't actually do anything yet (actual support for _using_ the metadata will come in another file).
Right now the TOML files are validated quite stringently: if a file contains the name of a property it doesn't understand, or the type of the property is wrong, it will raise an error. We can revisit this if it becomes burdensome.
This adds basic support for nesting (#17). It does not swap fill/stroke colors based on the position of the nesting box, though. It also only nests a symbol in the eye creature and "bonkers" complexity setting for now--support for nesting in complexity levels 1-4 is forthcoming.
The nested symbol is essentially uniformly scaled as much as possible without extending outside the boundaries of its parent's nesting box.
Nina Paley