r4006 802.1Q: Recalculate downlinks/uplinks button. Used in cases when due to some...

r4006 802.1Q: Recalculate downlinks/uplinks button. Used in cases when due to some action
(order change, link add) port vlan configs are not consistent.

inc/interface.php:
 renderObject8021QPorts: new button added under port list

inc/functions.php:
 recalc8021QPorts: new function to recalculate uplinks and downlinks on the specified switch,
                   and also its corresponding remote ports. Can be useful in script mode.
 produceDownlinkPort: new function to duplicate remote side uplink port config as local side downlink. Used by recalc8021QPorts.
 queueChangesToSwitch: updates D-config and mutex_rev if new port config differs from the old one.