flow: more generic functions and split states into own module
flow: abstractify bundle index
flow: flesh out States instances
flow: flab around on state management
flow: genericize watch operators
flow: make group, pack and folds generic
flow: make IO functions generic
flow: add simple wrappers around generic IO
flow: get vector ops back
flow: define simple flows via type synonym to avoid wrapping and unwrapping
flow: remove old vector IO, this is now generic IO
flow: define chunked streams in terms of generic ones
flow: doc wibble