Fast Finality in Filecoin tracking issue.

[ruseinov]

Investigate filecoin-project/FIPs#809 and estimate how long that will take to implement.

Things to do:

• Investigate the proposal and assess it's viability.
• Roughly estimate how long it would take to implement.
• Implement the proposed algorithm
• Integrate the implementation

[ruseinov]

I've been reading the doc and the discussion, it seems there are a lot of gaps in the original doc, which were supposed to be filled by another mentioned here.
It's been promised a while ago, but I'm unsure if it got released to the public yet.

[lemmih]

Can #4552 replace this issue?

[ruseinov]

superseded by #4552