v0.18.0

• Add box.profile() to access 3Box profile data (#109).
• Add areweave.transactionData() to access Arweave transaction data (#109).
• Add Bytes.fromUTF8() helper to create byte arrays from strings (#78).
• Add json.try_fromBytes() for handling JSON parsing errors (#110).
• Add a DataSourceContext class for SomeTemplate.createWithContext()
  (#106, #108).
• Add support for calling overloaded Ethereum contract functions (#100).
• Add a Babylonian .sqrt() method to BigInt (#104).
• Move Ethereum integration into a dedicated ethereum module. Rename
  types from EthereumBlock to ethereum.Block etc. (#99).