Enable native IPv6 support by default

git-svn-id: svn://svn.openwrt.org/openwrt@36277 3c298f89-4303-0410-b956-a3cf2f4a3e73
Adapt default network configuration for IPv6

git-svn-id: svn://svn.openwrt.org/openwrt@36278 3c298f89-4303-0410-b956-a3cf2f4a3e73
Remove obsoleted ipv6-support meta-package

git-svn-id: svn://svn.openwrt.org/openwrt@36279 3c298f89-4303-0410-b956-a3cf2f4a3e73