Now that we have a global `Ecc` instance, and `new Ecc` is basically a no-op, we can remove a lot of the `ecc: Ecc` params that are needed to use ecash-lib, simplifiying usage quite a bit.
The `TxBuilder.sign` function now receives a `params` object instead of a parameter list, which makes the code more readable.
This is a breaking change for both ecash-lib and ecash-agora, which we bundle in with the `initWasm` removal.