pfSense

Fix #6828

Until 2.3.x pfSense carried a patch that changed the behavior of 'route
change' command, making it add the route when it fails to change.
On 2.4 this patch was removed and will not be added back. This change
adjust PHP code to deal with route add / change and make it work...

Move copyright from ESF to Netgate

Move to Apache License 2.0

Review license / copyright on all files (1st round)

Use named variables for ppp-linkup command line parameters

Connect ppp-ipv6 helper script to ppp-linkdown and ppp-linkup

Introduce read_xml_tag.sh

Create /usr/local/sbin/read_xml_tag.sh, that will read a xml tag from
config file using xmllint. Replace all direct read using cat, grep, sed,
... by this script

Move main pfSense content to src/