OP_EXPIRE: Mitigating replacing cycling attacks

@mpch I had been experimenting with replacement cycling using Warnet, but my experiments were all from before the refactor that jonas mentioned. They mostly use a replacement cycling example created by ariard. You can find them here:

As jonas mentioned, the Warent team is gearing up with a new system to deploy lightning nodes into Wanret and also a new plugin system to make it easier for users to add functionality.