(cherry picked from commit 4941dd32)

(legacy) make disablevlanhwfilter optional + redirect on successful save in system_advanced_network.php

(cherry picked from commit 2fc3baa9)

(cherry picked from commit 3542a33e)

fix mtu parent setting and add max-payload for pppoe

(cherry picked from commit 0953e762)

(cherry picked from commit c3894df0)

(cherry picked from commit 0be62650)

(cherry picked from commit b57f2415)

(cherry picked from commit 8fce959f)

The widget collection needs a cleanup, but is not at the top of the priority list. Lets make sure the legacy functionality delivers output and make sure the already cleaned components stay that way.

(cherry picked from commit d4d07fbb)

(cherry picked from commit 53df54fc)

(cherry picked from commit 6a6f7f3b)

(cherry picked from commit 2de658b9)

o Add $waitforit flag to killbypid() and use it to simplify code.

o When requesting a configure via id, do not exclude the service
  because it is disabled.  The pidfile needs to be killed still.

o Unwind the convoluted code paths in the VPN plugin during early
  configure: kill service, probe for active, then do work.

(cherry picked from commit 2ddb95f7)

This will make a few good people very happy.  :)

(cherry picked from commit 0d70b4a9)

(cherry picked from commit 234f54d8)

(cherry picked from commit 22ed3586)

(cherry picked from commit 55188651)

(cherry picked from commit 928d169c)

(cherry picked from commit 404caff1)

(cherry picked from commit 204e93a7)

(cherry picked from commit 9fdca300)

(cherry picked from commit 8594ccea)

(cherry picked from commit 23ac5a28)

(cherry picked from commit 14a40cf7)

(cherry picked from commit b6cfa710)

(cherry picked from commit 6d7d0bc3)

(cherry picked from commit 3b42ee7e)

This way, the caller only needs to specify plugins.inc on the
top to let the subsystem(s) know plugin hooks need to be executed.

(cherry picked from commit e8fa56c5)

This is done so that services.inc can load plugins when
plugins.inc was invoked, if not, it stays clear of the
extra work.

(cherry picked from commit 669f6e03)

(cherry picked from commit 269b9b6a)

(cherry picked from commit 4635ac7b)

(cherry picked from commit 40516e54)

(cherry picked from commit 07bafdf6)

(cherry picked from commit 9709336b)

The rules are simple:

* plugins_configure() requires all available plugins, probes their
  configure functions and then calls the advertised functions.

* All GUI pages must directly include their includes in plugins.inc.d
  to not overly pollute their loading phase.

(cherry picked from commit cbd9ffb5)

(cherry picked from commit c9b70766)

(cherry picked from commit 93e47fac)