TOC generation, sorted

[sam-github]

Would it be possible to make the TOC be sorted within levels, without rearranging the document? Basically, decouple markdown from TOC.

Example markdown content (just subjects, no content):

# deserts
## pie
## cake
# apples
## yellow
## red

Normally the TOC exactly reflects the document, I'd like if (at least optionally) could be alphabetized, so the above would look like:

TOC:

1. apples
  1.1 yellow
  1.2 red
2. desert
  2.1 pie
  2.2 cake

I would find this particularly helpful for things like fs, where the content might be grouped "functionally" - file open/close/read/write are grouped together, stat/lstat are together, but when looking at the toc it would be better to see things in an alphabetized order.

Or maybe this is crazy, and the docs should just get reordered?