Hold main lock for less time

When we open a file, we grab the mutex for that file, rather than
continuing to hold the main mutex during the open() operation
Make response delay more generic.

For now, it only applies to Access-Reject packets
Sanitize return codes.  "do nothing" is NOOP
Added hextobin xlat.

It's useful for creating binary nonsense
use the correct name
Remove unused argument
Use talloc_free.  Fixes #582
Revert "Create reply attributes parented from the reply"

The changes required are more extensive.

This reverts commit 4d9b7afbd9c5bf14fb4166a58ef5e46c67f7da7b.
Fix calls to radius_paircreate()

It now takes a CTX rather than a REQUEST.  And all callers
use the correct context.
"i" is needed only if we have threads
Cast to const
Allow DHCP NAKs to be delayed

via response:FreeRADIUS-Response-Delay
Complain about blocked only on the first pass through the queue
Run Post-Proxy-Type fail on no reply.  Fixes #576
Formatting
Convert "%{Attribute-Name}" to just &Attribute-Name

which should speed things up slightly at run time.
Distinguish failure modes
Tests for new compilation
Use packet for VP context
Allocate from the local map ctx