This is intense, as we still want to preserve the serializer for V1 &
V2, and I've tried as much as possible to avoid polluting the
application layer with many enum types such as:
```
pub enum TxOut {
V1(TransactionOutput),
V2(TransactionOutput),
V3(TransactionOutput),
}
```
Those types make working with the script context cumbersome, and are
only truly required to provide different serialisation strategies. So
instead, we keep one top-level `TxInfo V1/V2/V3` type, and we ensure
to pass serialization strategies as type wrappers.
This way, the strategy propagates through the structure up until it's
eliminated when it reaches the relevant types.
All-in-all, this strikes a correct balance between maintainability and
repetition; and it makes it possible to define _different but mostly
identical_ encoders for the various versions.
With it, I've been able to successfully encode a V3 script context and
match it against one produced using the Haskell libraries. More to
come.
KtorZ