cr is short for change-run. It runs a command with every change to the working
directory tree. Usage example:

    $ cr bazel test --test_output=errors ...

cr depends on inotifywait, usually found in the inotify-tools package.

For use in docker, include these lines in the Dockerfile:

    RUN wget https://raw.githubusercontent.com/gsf/cr/master/cr \
      && chmod +x cr \
      && mv cr /usr/local/bin/