Overview of changes:

 *  Relaxed shellfu-bash-jat version range

    xcase and jat don't need to go hand-in-hand, so this is more of a
    burden than advantage.  Especially when jat is still in the stage
    when it needs to move fast.

 *  Codebase maintenance

Overview of changes:

 *  Banned @ from xcase__enum()

    Since case ids now can become part of jats:// ids, it's better to
    allow minimal set and avoid confusion.

 *  Made use of multi-line logging in latest jat.sh

 *  Added case ids to JAT phases

 *  Removed forgotten beakerlib-ism

 *  Codebase maintenance

Turns out that case ids may end up being re-used in URI contexts, and
'@' has special meaning in some parts of URL (HTTP, at least), which
could cause confusion or make translations to HTTP URLs troublesome.

Since it looks like it's not used anywhere yet, it's safer to drop it.