pfSense

Fix undefined and unused variable warnings in interfaces.inc

Notes: * interfaces_tunnel_configure() * loop continue on address type "track6" never hit, defined variable is
'$ipaddrv6' but was referred to as '$ipaddr6' * interface_bring_down() * '$old_router' was populated with the contents of a file but never used...

Replace direct config array accesses in interfaces.inc

Replace config array accesses in create_interface_list()

Fix multilevel array access outside config in util.inc

• Add generic array get/set path and path_exists functions to util.inc
• Wrap these more generic versions with the confg_* equivalents

Make list assign from explode output safer

• Make the explode limit to the number of expected items
• Assign values by array_shift() to prevent undefined key warns

Fix some undefined variable warnings

Correct single quoted string with parameter expansion

Silence unused/undef'd variable warnings in filter.inc

Replace multilevel config array access around the web gui port

Replace multilevel config array accesses regarding openvpn