* Introduce simple blockchain runtime for substrate tests.
* Remove bad files.
* Add needed wasm binaries.
* Refactoring.
- Repot files in test-runtime.
- Rename troublesome `Joiner::join` to `Joiner::and`.
- Rework `Slicable` to dedup code.
* More fixes and refactoring
* Rebuild substrate test wasm.
* Fix merge errors.
* Rename the disasterously named `to_vec` to `encode`.
Also rename `as_slice_then` to `with_encoded`.
* Tests for toy runtime.
* Fix doc nit