* more revision control systems

* 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.

* offline support

  If I commit something to git while offline, it would be nice if mr could
  have a way to push that change when I get online.

  One approach would be to notice when mr commit fails, and queue the
  commit up to be tried happen again when "mr retry" is run. This could
  also notice other failing commands, such as "mr up".

  Would it make sense to have to first run "mr offline", before mr starts
  recording such failures? If so, "mr online" would be the thing to run
  when getting back online, this would both retry queued commands, and stop
  queuing new failures.

  One annoying thing is that, if offline, dns timeouts can take a while in
  certian situations. So, it might be good to have a "mr remember <command>",
  to directly add a command for mr to run when coming online, without
  the need to run the command and wait for it to fail.