bake: Fix bugs introduced by bake optimizations, of course. - Make the execution stats JSON-serializable. - Re-add ability to differentiate between sources used during segment rendering and during layout rendering. Fixes problems with cache invalidation of pages that use other sources. - Make taxonomy-related stuff JSON-serializable.

---
args: showconfig
---
config:
    site:
        root: /something
args: showconfig site/root
out: /something/