NetworkManager: add dnsmasq.d/mikaela.conf

I want DNSMasq to behave a little differently from the NetworkManager
defaults.

The default cache size of 150/400 seems a little small and 10 000 probably
won't be full soon and I am sure modern systems at least at home where I
am using dnsmasq again won't suffer from it.

By default dnsmasq started by NEtworkManager only listens on 127.0.0.1
while ::1 also exists, I want it to be also listened on in case anything
decides to try querying with it.

DNSSEC is not checked by default while I want that behaviour, but as I
am using OpenDNS I cannot make it verify unsigned zones are unsigned :(

Also add symlink to trust-anchors.conf that should ship with DNSSEC to
avoid having to deal with it manually. It should work as a reminder that
it's also needed.

etc/NetworkManager/dnsmasq.d/mikaela.conf

@@ -0,0 +1,14 @@
+# Default 150, 10 000 probably won't hurt with RAM of modern devices
+cache-size=10000
+
+# Also listen on IPv6 localhost
+listen-address=::1,127.0.0.1
+
+# Attempt to verify DNSSEC
+# ln -s /usr/share/dnsmasq/trust-anchors.conf trust-anchors.conf
+#                  dnsmasq-base on Ubuntu
+dnssec
+
+# Verify that DNSSEC is not stripped, disabled thanks to OpenDNS, to be
+# enabled if they ever stop that behaviour (I hope).
+#dnssec-check-unsigned

etc/NetworkManager/dnsmasq.d/trust-anchors.conf

@@ -0,0 +1 @@
+/usr/share/dnsmasq/trust-anchors.conf