Store site data separately

[denisdefreyne]

nanoc.yaml is currently used for configuration as well as storing site data. Splitting this up in nanoc.yaml (for configuration) and site.yaml (for site data) would help:

• Be able to define a scheme for nanoc.yaml and validate it
• Create site data without the fear of overwriting built-in config data

Filters and helpers could have their (default) configuration in a sub-hash, e.g.

helpers:
  render:
    super_fast_rendering: true

checks:
  internal_links:
    exclude:
      - whatever