Twiddling prompts

You will now be able to control whether to see the twiddling
(/-\|/-...) promptor not, separately from "spam" mode.

This will be done using "prompt twiddlers":

 > prompt twid
 Your prompt will display twiddlers when you are busy.

Note that only if you are in spam mode, will "prompt all" turn on
twiddlers.

- Dain