[PATCH 0/7] StGIT, remotes, and parent

This new series should bring the first 5 patches into sufficiently reasonable shape, so I'm presenting them for inclusion. The last 2 ones are still there for context only.

This new revision of the series brings:

- Better use of stgit.config in subsequent patches, notably deported
the remaining call to repo-config into stgit.config:
config.sections_matching(regexp)

- Caching in stgit.config.  I implemented this as on-demand caching,
initially because it was straightforward, but it turns out that
sections_matching() naturally fits in this model, and i'm not sure how
we could have implemented this in the pre-caching model.

- The usual bunch of misc cleanups.

Best regards,