Fix default_theme to render all parameter properties.
- Split the parameter property template portion into its own partial.
- Have the new partial recursively call itself if there are sub-properties.
* build: Use Flow syntax without comments.
We're switching to Flow annotations - not Flow comments. This
gives documentation.js the ability to self-document without
JSDoc types and improves our compatibility with tools like
prettier.
Fixes#729. Fixes#709
