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.
This fixes#21 by changing the existing "tail" attachment point (`#ff0000`) to be called the "anchor" attachment point, since that's primarily what we're using it for. It also adds a brand-new "tail" attachment point with color `#be0027`, which is expected to be oriented in the direction the tail should point (not the _opposite_ direction of the tail, which is how the old tail attachment point was oriented).
Note that this change means, for now, that no symbols have tail attachment points. An error will be logged in the console when viewing the "Creature!" page for now because of this (since the default composition attaches a symbol to the tail), but as soon as Nina updates the SVGs, this should go away.
This attempts to manually scale the strokes on creatures so they aren't affected by scale.
The weird thing here is that applying `vector-effect="non-scaling-stroke"` does not appear to do the trick--rather, it makes all the strokes look _super heavy_. So in this PR we scale the stroke by the inverse of whatever we're cumulatively scaling by when we're drawing something.
This fixes a bunch of bugs in our attachment-related code, and in so doing refactors things to make more sense, adds more tests, and also adds documentation.
Atul Varma