Add default case when detecting dynamic gateway ip

Add a default to $wancfg['ipaddr'] case for both ipv4 and ipv6 to allow gateway ip to be returned rather then 'dynamic' for an openvpn connection
Merge pull request #575 from avandeweghe/patch-1

Add default case when detecting dynamic gateway ip
Install Plan B for upgrading the RRD files to the newer format to add IPv6 fields.
We now perform a search and replace on the XML contents to add fields instead of reading the XML into a PHP array.
A conversion with a 2.0 config on a 128MB VM without swap is succesful, needs more testing.
Ticket #2950
Tidy up "interfaces_group_edit.php" XHTML

Tidy up escaped forward slash in Javascript
Tidy up "interfaces_gre.php" XHTML

Move NOWRAP to class statement
Close BR and IMG tags
Deprecate ampersand in ANCHOR tags
Tidy up "interfaces_gre_edit.php" XHMTL

Update HTML Boolean operators
Close BR and INPUT tags
Tidy up "interfaces_gif.php" XHTML

Move NOWRAP to class statement
Close IMG and BR tags
Deprecate ampersand in ANCHOR tag
Add missing closing P tag
Tidy up "interfaces_gif_edit.php" XHTML

Update HTML Boolean operators
Close INPUT and BR tags
Tidy up "interfaces_bridge.php" XHTML

Close BR and IMG tags
Deprecate ampersand in ANCHOR tag
Tidy up "interfaces_bridge_edit.php" XHTML

Add CDATA section to SCRIPT tags
Update HTML Boolean operators
Close INPUT and BR tags
Add missing closing P tags
Add missing closing TD tag
Add missing closing SPAN tag
Remove duplicate closing TD tags
Tidy up "interfaces_lagg.php" XHTML

Move NOWRAP to class statement
Close IMG and BR tags
Deprecate ampersand in ANCHOR tag
Add missing closing P tag
Tidy up "interfaces_lagg_edit.php" XHTML

Update HTML Boolean operators
Place the class statement from the SPAN into the UL tag and remove the
SPAN tag
Close INPUT and BR tags
Tidy up "interfaces_pps_edit.php" XHTML

Close INPUT and BR tags
Tidy up "interfaces.php" XHTML

Update HTML Boolean operators
Close a couple of missed INPUT tags
Merge pull request #576 from ExolonDX/branch_02

Tidy up "interfaces_group_edit.php" XHTML
Merge pull request #577 from ExolonDX/branch_03

Tidy up "interfaces_gre.php" XHTML
Merge pull request #578 from ExolonDX/branch_04

Tidy up "interfaces_gre_edit.php" XHMTL
Merge pull request #579 from ExolonDX/branch_05

Tidy up "interfaces_gif.php" XHTML
Merge pull request #580 from ExolonDX/branch_06

Tidy up "interfaces_gif_edit.php" XHTML
Merge pull request #581 from ExolonDX/branch_07

Tidy up "interfaces_bridge.php" XHTML