[rfc] developer documentation on user interaction

[Stephen J. Turnbull]

Vincent Ladeuil writes:

 > Adding command line options because some GUI tool need them
 > doesn't seem like the best way to make a nice and clean CLI.

The problem is, as Alexander says, that the CLI is *much* more stable
than the API.  *In hindsight*, I am not at all surprised.

1.  Other tools such as git and hg show similar behavior.  It is far
    easier and more maintainable to script them than it is to use the
    internal APIs.

2.  The audience for the CLI demands stability; the audience for the
    API demands features.

I think "Although practicality beats purity" applies.