Quite some inconsistencies in this function, parameters that can't be set, lack of logic and code duplication.

* removes get_configured_pppoe_server_interfaces(), which can't work anyway... pppoe server interfaces are registered via the plugin itself.
* $dhcpv6ifconf['mode'] can't be set anywhere....
* don't try to revalidate rainterface
* collect "real interface" from dhcpif, shouldn't use carp if
* remove code duplication in dns collection
* move checks up for interface we should skip (when possible)
* RA subnets do not have any backend ties

PR: https://github.com/opnsense/core/issues/1196

(cherry picked from commit 607d8ecc)
(cherry picked from commit b3737522)
(cherry picked from commit 089a3f07)
(cherry picked from commit 89c7a39f)

Credits: https://redmine.pfsense.org/issues/4111
(cherry picked from commit 71275241)

(cherry picked from commit 0080f3f4)

(cherry picked from commit 7cf77968)
(cherry picked from commit 342757b4)
(cherry picked from commit a02b02fa)

(cherry picked from commit 721705d1)

(cherry picked from commit 7b07e6a5)

Some minor tweaks in the file, e.g. we shouldn't use gettext()
for most tings, don't need translations in config files or for
strings that are hardly translatable (OpenVPN).

(cherry picked from commit 33d1edc8)

o consolidate "unbound_" prefix for unbound.inc for pluginification
o services.inc includes unbound.inc rightfully, a bit like a
  plugin would do in the future, but this also means we can
  zap all requires from top pages, which are entirely spurious.
o get_dns_servers() moves to system.inc because it is used by
  status_interfaces.php
o RIP read_hosts()

(cherry picked from commit 715b6367)
(cherry picked from commit cdb0c667)

(cherry picked from commit 18d46de7)

(cherry picked from commit 408ebbef)

(cherry picked from commit a9b8f965)

This was done in early 16.7, seems to work fine so finish the
transition, dnsmasq is next...

(cherry picked from commit 20b39395)

(cherry picked from commit 7c4443a8)

PR: https://forum.opnsense.org/index.php?topic=3884.0
(cherry picked from commit 54c476a9)

192.254 is a legal IPv4 range.
169.254 is the correct private IPv4 address space.
Moved the order of the private address.
(cherry picked from commit 6c87cd42)

(cherry picked from commit bd6c048d)
(cherry picked from commit 438ad5b7)
(cherry picked from commit bd6d928a)
(cherry picked from commit 8ab6fb4c)
(cherry picked from commit 6d2a95ae)
(cherry picked from commit a5e7a055)
(cherry picked from commit d35678f1)
(cherry picked from commit 1c1d4e07)
(cherry picked from commit 505c27c6)
(cherry picked from commit 7ad477ca)

(cherry picked from commit d0206619)

(cherry picked from commit ec92f844)

(cherry picked from commit c1628bbf)
(cherry picked from commit 3a25b4b7)
(cherry picked from commit 4c253df1)

(cherry picked from commit 78945ce0)

There may be more, at least I don't see the difference between
TLS and shared key for most settings, except certificate setup.

The client traffic redirect is probably also wrong, but for now
provide consistency with TLS.

PR: https://forum.opnsense.org/index.php?topic=3908.0
(cherry picked from commit 6a018ead)

o > 16 hours of randomisation is too much, let cron jobs
  run within 15 minutes.
o Move to `jot' utility for better visibility/portability.
o switch the default bogons invoke to right now, only
  defer the run if `cron' argument was given.

(cherry picked from commit 23530144)

(cherry picked from commit a8bcef6b)
(cherry picked from commit 3486cd2a)

(cherry picked from commit 0cf04fbe)

(cherry picked from commit 72d69220)
(cherry picked from commit dd50e688)

(cherry picked from commit c8c7e364)

(cherry picked from commit 1328c754)

(cherry picked from commit 2d08f304)

Submitted by: @fbrendel

(cherry picked from commit 3cf976cd)

(cherry picked from commit fb99cf44)

(cherry picked from commit 7116568b)

(cherry picked from commit 2dde9b7c)

(cherry picked from commit 593f9b77)

This is the proper way to handle bootup output for the
console: request it and don't output ever time it's called
during boot....

(cherry picked from commit 2c045731)

(cherry picked from commit 65c53e3c)

(cherry picked from commit 74ca8331)

(cherry picked from commit 015c5d00)
(cherry picked from commit a9f41407)

(cherry picked from commit a000c8e0)