Disable the spinner when kat is used non-interactively

[arrdem]

When starting the backing Katamari server, the kat script displays a little single character shell spinner, which works great in a terminal emulator and not so great if you're in a CI context, or using Unix pipes.

The kat script should be extended with logic to detect whether the parent terminal is interactive or not, and skip the spinner machinery if the parent term is non-interactive. It should also be possible to disable the spinner with a flag to the kat script, or a kat.conf setting.