Add missing authorization check on !igset.
Move delay min/max to job settings.

This will eventually be used to permit runtime modification of
inter-request delay time.
Permit separate delay range for page requisites.

Browsers generally fetch all page requisites (e.g. images, CSS) as fast
as possible.  We're (usually) okay following in their footsteps.
Style fix.
Add !d(elay) and !reqd(elay) commands.
Document !delay and !reqdelay.
Bump pipeline version for the new delay code.