luci-proto-ipv6: Add support for IPIP6(RFC2473) tunnel

[missing233]

Add Generic Packet Tunneling in IPv6 Specification (RFC 2473) support.
(For NTT Broadband V6Plus/transix/Xpass Fixed IP)

depends on other PRs: openwrt/openwrt

[systemcrash]

OK @missing233 go ahead and resolve those conflicts and force push. When the parent PR openwrt/openwrt#14516 lands in master, go ahead and set this to ready.

[systemcrash]

Rebase on current master to resolve conflicts

[missing233]

Rebase on current master to resolve conflicts

Rebase on current master to resolve conflicts

Done.
Thanks :)

[systemcrash]

Rebase on current master to resolve conflicts

Rebase on current master to resolve conflicts

Done. Thanks :)

Were that so, github would not say: "This branch is out-of-date with the base branch" :)

[systemcrash]

So you need to at least: change to master, git pull, check out ipip6, rebase, ...

[missing233]

OK @missing233 go ahead and resolve those conflicts and force push. When the parent PR openwrt/openwrt#14516 lands in master, go ahead and set this to ready.

Ok it's now ready.

[systemcrash]

OK. In she goes. Thanks @missing233

[systemcrash]

This is in tandem with openwrt/openwrt@21eeb45