Add changes to ergo-core readme

extract PoPowAlgosSpec -> PoPowAlgosWithDBSpec

extract SerializationTest -> SerializationCoreTest

extract JsonSerializationSpec -> JsonSerializationCoreSpec

move scorex.testkit.SerializationTests -> ergo-core/org.ergoplatform/utils

NiPoPoWVerifierSpec has to stay in node's test since ChainGenerators it requires uses ErgoHistory

Create ChainSettingsReader in ergocore

Refactor generators to use Object instead of trait. To avoid OOP inheritance spagetti

Remove scores.testkit.CoreGenerators

Move scorex.testkit.generators.ObjectGenerators -> ergo-core/org.ergoplatform.utils.generators.CoreGenerators

Extract ergo-node specific ConnectedPeerGenerators from CoreGenerators

Move DefaultFakePowScheme to ergo-core

Dissect ErgoTestConstants into ErgoCoreTestConstants & ErgoNodeTestConstants

Move settings.LaunchParameters to ergo-core

Dissect ErgoTransactionGenerators into ErgoCoreTransactionGenerators & ErgoNodeTransactionGenerators

Dissect part of VotingSpecification to ErgoNodeVotingSpecification

fix test 'valid application of correct extension'

fix test 'validation of field value sizes'

provide alternate test-generators

Add ergo-core testing and publishing snapshot on PR branch push

Fix ergo-core multiversion tests