- Introduce SourceT, which is simple variant of "correct `ListT`".
There are another variants possible (like in `streaming`),
but I'm not sure there's much real difference.
- Introduce `Codensity`. There's a flag if people don't want to depend
on `kan-extensions`.
- `StreamGenerator` and `ResultStream` are both `SourceT`.
`Stream` combinator in `servant-client` uses `Codensity` for CPS.
- Add servant-machines, servant-conduit, servant-pipes
- Add streaming cookbook: just code, no explanations.
- Add a script to run streaming 'benchmarks'
This commit begins the reorganization of the servant-client project
so as to allow multiple backends, and also begins some much-needed
refactoring of the servant-client code.
