Add stable sortEvents function

[alexgleason]

Adds a function to sort events, which is often needed when gathering events from untrusted sources such as relays.

Events are sorted reverse-chronologically by the created_at timestamp. If there is a tie with created_at, it sorts lexicographically by the event ID.

[fiatjaf]

NIP-01 says this about replaceable events:

In case of replaceable events with the same timestamp, the event with the lowest id (first in lexical order) should be retained, and the other discarded.

Does this match your function?

[alexgleason]

Yes it does :+1: Cool.