Switch some talloc_free's to TALLOC_FREE's
Clarify comment
More debugging for evaluation

protected by a #ifdef, so normal people don't see it
Load protocol-specific dictionaries if built with them.

The code in parser.c does static evaluation of things like

	if (DHCP-foo == ...)

When the DHCP dictionaries aren't loaded, that turns into static
comparison of two strings, which is always false.  Changing it to

	if (&DHCP-foo == ...)

makes it bail with an unknown attribute error.  This is because
we don't have pass2 fixups for that case.
Space for clarity
Clarify error message
Minor formatting in dhcp.c
don't respond to dhcp if there is nowhere to respond to