New sandbox release!

sandbox v0.9.0 has been released. It contains two new features:
- A gas usage helper, printTransactionFees, that you can call on an array of transactions acquired from a sandbox execution, to help you calculate the fees of your operations
- Snapshots for Blockchain and SmartContract. Here's how to use them:

const snapshot = oldBlockchain.snapshot()
const newBlockchain = await Blockchain.create()
await newBlockchain.loadFrom(snapshot)

These features were discussed in our community prior to their release, so join us, if you want to discuss other stuff!