bake: Optimize cache handling for the baking process. - Get rid of the 2-level pipeline runs... handle a single set of passes. - Go back to load/render segments/layout passes for pages. - Add descriptions of what each job batch does. - Improve the taxonomy pipeline so it doesn't re-bake terms that don't need to be re-baked. - Simplify some of the code.

---
config:
    what: not good
config_variants: [test]
in:
    pages/_index.html: 'This is {{what}}.'
    configs/test.yml: 'what: awesome'
out:
    index.html: 'This is awesome.'
---
config:
    what: not good
config_values:
    what: awesome
in:
    pages/_index.html: 'This is {{what}}.'
out:
    index.html: 'This is awesome.'