miniupnpd: Import release 20180422 to repo

Import miniupnpd from routing repo and bump to 20180422.

Drop 102-ipv6-ext-port.patch as this looks upstreamed in the pinhole
code to me.
Consolidate all other patches & update with a view to sending upstream.

Add support for runtime IGDv1 mode switch (default to IGDv2)

(not extensively) Tested-on: ar71xx Archer C7 v2 in IGDv1 compatibility
mode.  A variety of devices/applications appear to be able to create
mappings.

Have an attempt at resolving https://github.com/openwrt-routing/packages/issues/286
TL;DR miniupnpd rules get processed before fw3 rules and thus can
override existing/intended redirects.  Ideally the miniupnpd rules would
be last in the relevant chains, unfortunately fw3 can sometimes use the
last rule as a REJECT.  Put miniupnpd rules as penultimate.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>

net/miniupnpd/files/miniupnpd.hotplug

@@ -0,0 +1,33 @@
+#!/bin/sh
+
+/etc/init.d/miniupnpd enabled || exit 0
+
+. /lib/functions/service.sh
+
+# If miniupnpd is not running:
+# - check on _any_ event (even updates may contribute to network_find_wan*)
+
+# If miniupnpd _is_ running:
+# - check only on ifup (otherwise lease updates etc would cause
+#   miniupnpd state loss)
+
+[ "$ACTION" != "ifup" ] && service_check /usr/sbin/miniupnpd && exit 0
+
+tmpconf="/var/etc/miniupnpd.conf"
+extiface=$(uci get upnpd.config.external_iface)
+extzone=$(uci get upnpd.config.external_zone)
+
+. /lib/functions/network.sh
+
+if [ -z "$extiface" ] ; then
+  # manual external zone (if dynamically find interfaces
+  # belonging to it) overrides network_find_wan*
+  if [ -n "$extzone" ] ; then
+    ifname=$(fw3 -q zone $extzone | head -1)
+  fi
+  [ -n "$extiface" ] || network_find_wan extiface
+  [ -n "$extiface" ] || network_find_wan6 extiface
+fi
+
+[ -n "$ifname" ] || network_get_device ifname "$extiface"
+grep -q "ext_ifname=$ifname" "$tmpconf" || /etc/init.d/miniupnpd restart