Removing expiry dates for TOFU

[Petite Abeille]

> On Jul 9, 2020, at 00:18, Solderpunk <solderpunk at posteo.net> wrote:
> 
> Thanks for sharing this!  I will read it closely.  It's a shame if it's
> not widely implemented, but there may well still be good ideas in there,
> or details we've overlooked.

Another link, as a counterexample of what we are trying to escape from:

Path Building vs Path Verifying: The Chain of Pain
https://medium.com/@sleevi_/path-building-vs-path-verifying-the-chain-of-pain-9fbab861d7d6

The Chain of Pain! :D