Improve edit post function - expose iterations

Summary

Fix the gaps with the edit function to avoid manipulation.

Goals

• ‘Edited’ text should link to full edit history of the post so you can see what changed

• All engagement should be reset to zero when a post is edited

Risks of current system

• users can make a post trend, then change it to something completely different to change the context

• people who voted on an initial post may no longer agree with the edit