Preserve user's category/section ordering

[njsmith]

Right now the config reading code carefully uses OrderedDicts to preserve the user's section and category ordering. Later, we throw this away, and sort them alphabetically.

I want features to come before bugfixes. It's not my fault that "f" comes after "b". Please don't make me call them addedfeatures or something ridiculous like that.

I think all this would take is replacing all the dicts in render_fragments with OrderedDicts, and then dropping the dictsorts from the template. I'd do it myself, but it'd create even more conflicts with my outstanding PRs... (please merge my PRs).