To avoid a memory leak in DNS lookups that's hard to work around and
does not otherwise effect typical operation when Zeek is allowed to
continue to run after zeek_init().
For backward compatibility when reading values, we first check
the ZEEK-prefixed value, and if not set, then check the corresponding
BRO-prefixed value.
This also installs symlinks from "zeek" and "bro-config" to a wrapper
script that prints a deprecation warning.
The btests pass, but this is still WIP. broctl renaming is still
missing.
#239
