Rune functionality moved into core from commando plugin.
Changelog-Added: JSON-RPC: `checkrune`: check rune validity for authorization; `createrune` to create/modify rune; `listrunes` to list existing runes; `blacklistrune` to revoke permission of rune
Changelog-Deprecated: JSON-RPC: `commando-rune`, `commando-listrunes` and `commando-blacklist`.
No-schema-diff-check
Rusty Russell