There were too many synchronisation problems with using the former;
including situations such as a "make clean" performed between two
installs to the same DESTDIR would result in a truncated METALOG and
the resultant sets would be missing stuff such as include files that
don't get reinstalled if they haven't changed, even with !UPDATE.
mention that PASSIVE_FETCH is the default in NetBSD-current, clarify
that many of the variables are only used inside the NetBSD packages
collection, document WINDOWMAKER_OPTIONS, move section no how to override
the MASTER_SITES_* to packages(7).
