Change the way the pacing of the ban-lurker is configured.

A new parameter, $ban_lurker_age, sets a minimum age bans must
have before the lurker will touch them.  This way the lurker
stays out of the "rush" that happens right after a ban has been
added.

Another new parameter, $ban_lurker_batch, determines how many
objects the lurker will examine, before it takes a $ban_lurker_sleep
in order to not monopolize CPU.
Introduce VCL_BLOB type which VMOD functions can use to pass
random bits of memory to each other.

I have added a "len" field to the vmod_priv structure and used that
for BLOB's.

We may need some memory-mgt beauty/convenience functions for this.
Don't clobber output on HUP
Don't clobber output on HUP
Fix spelling
More paranoia in the fetch processor.
Add a "inifin" facility to make Init/Fini activities happen in the
right order:  Init is done first to last "inifin", Fini is done
in opposite order, last to first.

This replaces the several ad-hoc facilities we had.