MacOS/bonjour compatibility and small typos

thank you for continuing development & support of this package. here are a few things to have it run on MacOS and to make it "bonjour-compatible" (-;

- the calls to addMembership and setMulticastLoopback are true if you want darwin to report multicast traffic from  remote hosts(addMembership) or the localhost(setMulticastLoopback).

- i have no idea why the package listens for unicast traffic, but if it's going to do so, it really ought to honor options.networkInterface

- for bonjour compatibility:
    - respond to SRV queries in addition to PTR/ANY queries
    - the SRV RR really out to be the first one
    - another PTR RR for _services._dns-sd._udp.local (this is the "magic bullet")

- the A RRs are _additional_ answers, and should go in the "right" section