* a way to detect repos in a tree that are not registered, and warn
  about or even auto-register them. (svn externals make this quite
  difficult!)

* When there are chained mrconfig files, mr could be smarter about
  checkouts and updates. Ie, when a new version of an mrconfig file is
  checked out or updated, throw all the info from the old one away, and
  process the new one.

  Until this is fixed, checkouts and updates need to be manually repeated
  after mrconfig files have changes. (See #447553)