* Add a dummy new blockimport type

* Switch to dummy block importer

* Move LatestAttestations to block_import mod

* Init LatestAttestations in ShasperBlockImport

* Wrap client BlockImport with custom fork choice

* Update bls version

* Re-introduce aggregate signature support

* Move DigestItem to a separate mod

* CompatibleExtrinsic trait

* Expose API for validator id from attestation

* CompatibleExtrinsic impl

* Save and load latest attestations

* note_block for LatestAttestation

* Expose last finalized/justified slot from runtime

* Implement LMD-GHOST's is_new_best

* Update substrate reference

* Finish LMD-GHOST integration

* Remove old unused lmd-ghost crate

* README: LMD-GHOST is integrated

* Switch to own DigestItem impl

* Fix consensus compile

* H256 -> Self::Hash

Rework Shasper and add block authoring logic

But note that this is incorrect according to eth2.0-specs BLS definition. It should be 48 bytes (and it's a G1, not G2).