[EPIC] Provide pandora consensus engine

[blazejkrzak]

[MIGHT BE CANDIDATE FOR MILESTONE/EPIC]

@currentSlot @synchronizedEpochList
Given as a Vanguard I want to produce consensus block
  And I have notified about validators that will be signing current epoch
  And in current slot I should create the block

When Pandora prepares the execution block for signature
  And notifies about it

Then Vanguard signs the block
  And Vanguard notifies about it
  And Vanguard asynchronously push this block to consensus peers
  And Pandora asynchronously push this block to execution peers

Expected behaviour

Engine is allowed to prepare block data and push it to the vanguard.

How to implement

Provide engine named pandora under consensus package.

[blazejkrzak]

https://gist.github.com/frozeman/d52090f3b8c4b654cacc279d894df31c

[blazejkrzak]

Here is a spike for it
https://github.com/lukso-network/pandora-execution-engine/pull/49

[blazejkrzak]

Spike now has some serious discovery and implementation about flow. Lets discuss it @frozeman @patred20 @mxmar @atif-konasl

[blazejkrzak]

We have prototype that works ATM.
Several issues yet to discover.
Related merge request #58

[blazejkrzak]

IMHO it requires refactor