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.

---
theme_config:
    site:
        title: "Some Test Theme"
in:
    pages/foo.html: "This is: {{site.title}}"
outfiles:
    foo.html: "This is: Some Test Theme"
---
theme_config:
    site:
        title: "Some Test Theme"
in:
    pages/foo.html: "This is: {{foo}}"
    configs/theme_preview.yml: "foo: bar"
outfiles:
    foo.html: "This is: bar"