TODO.txt

- `siteconfig ascp <ascp options> <base>`

- `siteconfig flags <command> --defaults='xxx' --add='xxx' --replace='xxx' <base>` somewhere we define the options for various commands, and this interpolates them for us, starting with the defaults, then the ones under {base}_{command}_FLAGS, then the overrides.

- "siteconfig_sources" entry_point, which merges the names into the basenames for
  the dir sources, then evaluates them all in order.

- lazy evaluation of config: the Config object should contain a list of config
  sources, which are evaluated as nessesary. When asked for a specific key, it
  walks from the front to the end of the list. When asked for everything, it
  starts at the top and moves to the bottom of the list keeping a set of keys
  that it reported on.

  ConfigSource API would have a load() method which should return the data, and
  the .data property would have logic to call that the first time.

- siteconfig.app.xxx:main functions for wherever there is a driver/hook/plugin
  what we want to specify via the siteconfig system. Then aque could look for
  drivers in a "aque_brokers" entry_point, where siteconfig would provide "siteconfig",
  which simply loads from the more standard aque brokers.

- don't load everything in siteconfig/__init__.py; make it lazy