json-rpc now requires nim-json-serialization to convert types to/from json. Use the nim-json-serialization signatures to call the json serialization lib from nim-codex (should be moved to its own lib)
Allows specified number of transaction confirmations to be awaited before a transaction is considered finalised. Polls for a transaction receipt then listens for new blocks and calculates the number of blocks between the receipt and the new block.
Notes
1. Only works with websockets currently
2. Replaced transaction not supported yet
