v2.8.1

Upgrade priority: Low. Recommended if using Substrate master with new MultiAddress.

Contributed:

• Export derive.chain.getBlock (Thanks to https://github.com/lovesh)

Changes:

• Expand MultiAddress construction with multi type detection
• Rename GenericLookupSource to IndicesLookupSource (internal use)
• Cleanup list retrievals with Raw data results for undecodable entries
• Export actual version via RegistryMetadata
• Dedupe bn.js (one version shared between dependencies)