near-api-js: Missing functionality checklist & discussion

Nearlib expected to be used by DApps and DWallets and it functionality should cover:

• Blockchain structure:
  • Block header by (block.number or block.hash)
  • Shard header by (block and shard.index) or shard.hash
  • Transaction header by (shard and transaction.index) or transaction.hash or account.nonce or address.nonce
  • Transaction header by (shard and transaction.index) or transaction.hash
  • Latest block number
  • Main coin balance
  • Merkle proofs of different structures
• Account management:
  • Transaction internal and external (hardware wallets) signing
  • Custom message signing similar to EIP-712
• Smart contract interaction:
  • Calling view methods of smart contract without on-chain tx
  • Creating transactions by forming method call arguments